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SubjectRe: [RFC v3 1/2] mmc: sdhci-msm: Add interconnect bus bandwidth scaling support
Hi Matthias,

Thanks for the review !

On 2020-02-08 06:12, Matthias Kaehlcke wrote:
> Hi Pradeep,
>
> On Fri, Feb 07, 2020 at 08:14:54PM +0530, Pradeep P V K wrote:
>> Add interconnect bandwidths for SDHC driver using OPP framework that
>> is required by SDHC driver based on the clock frequency and bus width
>> of the card. Otherwise, the system clocks may run at minimum clock
>> speed and thus affecting the performance.
>>
>> This change is based on Georgi Djakov [RFC]
>> (https://lkml.org/lkml/2018/10/11/499) and
>>
>> Saravana Kannan [PATCH v6]
>> (https://lkml.org/lkml/2019/12/6/740)
>>
>> change from RFC v2 -> v3 changes:
>> - Modified interconnect bandwidth support using OPP framework.
>> - Addressed review comments on v2.
>>
>> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
>> Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
>> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
>> Co-developed-by: Pradeep P V K <ppvk@codeaurora.org>
>> Signed-off-by: Pradeep P V K <ppvk@codeaurora.org>
>> ---
>> drivers/mmc/host/sdhci-msm.c | 251
>> ++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 247 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-msm.c
>> b/drivers/mmc/host/sdhci-msm.c
>> index 71f29ba..f061cd8 100644
>> --- a/drivers/mmc/host/sdhci-msm.c
>> +++ b/drivers/mmc/host/sdhci-msm.c
>> @@ -11,8 +11,10 @@
>> #include <linux/mmc/mmc.h>
>> #include <linux/pm_runtime.h>
>> #include <linux/slab.h>
>> +#include <linux/interconnect.h>
>> #include <linux/iopoll.h>
>> #include <linux/regulator/consumer.h>
>> +#include <linux/pm_opp.h>
>>
>> #include "sdhci-pltfm.h"
>>
>> @@ -229,6 +231,14 @@ struct sdhci_msm_variant_info {
>> const struct sdhci_msm_offset *offset;
>> };
>>
>> +struct sdhci_msm_bus_vote_data {
>> +
>> + struct icc_path *sdhc_to_ddr;
>> + struct icc_path *cpu_to_sdhc;
>> + bool skip_bus_bw_voting;
>
> nit: the name is somewhat redundant given the name of the containing
> struct. 'skip_vote' or 'skip_voting' would be sufficient IMO.
>
ok. i will address in my next patch series.

>> + u32 curr_freq;
>> +};
>> +
>> struct sdhci_msm_host {
>> struct platform_device *pdev;
>> void __iomem *core_mem; /* MSM SDCC mapped address */
>> @@ -255,8 +265,11 @@ struct sdhci_msm_host {
>> bool use_cdr;
>> u32 transfer_mode;
>> bool updated_ddr_cfg;
>> + struct sdhci_msm_bus_vote_data *bus_vote_data;
>> };
>>
>> +static void sdhci_msm_bus_voting(struct sdhci_host *host, u32
>> enable);
>> +
>> static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct
>> sdhci_host *host)
>> {
>> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> @@ -1564,6 +1577,7 @@ static void sdhci_msm_set_clock(struct
>> sdhci_host *host, unsigned int clock)
>>
>> msm_set_clock_rate_for_bus_mode(host, clock);
>> out:
>> + sdhci_msm_bus_voting(host, !!clock);
>> __sdhci_msm_set_clock(host, clock);
>> }
>>
>> @@ -1685,6 +1699,219 @@ static void
>> sdhci_msm_set_regulator_caps(struct sdhci_msm_host *msm_host)
>> pr_debug("%s: supported caps: 0x%08x\n", mmc_hostname(mmc), caps);
>> }
>>
>> +/*
>> + * Returns required bandwidth in Bytes per Sec
>> + */
>> +static unsigned long sdhci_get_bw_required(struct sdhci_host *host,
>> + struct mmc_ios *ios)
>> +{
>> + unsigned long bw;
>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
>> +
>> + bw = msm_host->clk_rate;
>
> nit: you could declare 'bw' last and do the assignment together with
> the
> declaration.
>
ok. I will do it in my next patch.
>> +
>> + if (ios->bus_width == MMC_BUS_WIDTH_4)
>> + bw /= 2;
>> + else if (ios->bus_width == MMC_BUS_WIDTH_1)
>> + bw /= 8;
>> +
>> + return bw;
>> +}
>> +
>> +/*
>> + * Helper function to parse the exact OPP node
>> + * Returns OPP pointer on success else NULL on error
>> + */
>> +static struct dev_pm_opp *find_opp_for_freq(struct sdhci_msm_host
>> *msm_host,
>> + unsigned long bw)
>> +{
>> + struct dev_pm_opp *opp;
>> + struct sdhci_host *host = mmc_priv(msm_host->mmc);
>> + unsigned int freq = bw;
>> + struct device *dev = &msm_host->pdev->dev;
>> +
>> +
>> + if (!freq)
>> + opp = dev_pm_opp_find_peak_bw_floor(dev, &freq);
>> + else
>> + opp = dev_pm_opp_find_peak_bw_exact(dev, freq, true);
>> +
>> + /* Max Bandwidth vote */
>
> s/Bandwidth/bandwidth/
>
ok.

>> + if (PTR_ERR(opp) == -ERANGE && freq > sdhci_msm_get_max_clock(host))
>> + opp = dev_pm_opp_find_peak_bw_ceil(dev, &bw);
>> +
>> + if (IS_ERR(opp)) {
>> + dev_err(dev, "Failed to find OPP for freq:%u err:%ld\n",
>> + freq, PTR_ERR(opp));
>> + return NULL;
>> + }
>> + return opp;
>> +}
>> +
>> +/*
>> + * This function sets the interconnect bus bandwidth
>> + * vote based on bw (bandwidth) argument.
>> + */
>> +#define BUS_INTERCONNECT_PATHS 2 /* 1. sdhc -> ddr 2. cpu -> sdhc */
>> +static void sdhci_msm_bus_set_vote(struct sdhci_host *host,
>> + unsigned int bw)
>> +{
>> + int i;
>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
>> + struct sdhci_msm_bus_vote_data *vote_data = msm_host->bus_vote_data;
>> + struct dev_pm_opp *opp;
>> + unsigned long freq = bw;
>> + unsigned long ib[BUS_INTERCONNECT_PATHS],
>> ab[BUS_INTERCONNECT_PATHS];
>
> the names are not very expressive, how about peak_bw and avg_bw?
>
hmm, ok. i will modify in my next patch set.

>> + int ddr_rc = 0, cpu_rc = 0;
>
> initialization is not needed
>
ok.
>> +
>> + if (!msm_host->bus_vote_data->sdhc_to_ddr ||
>> + !msm_host->bus_vote_data->cpu_to_sdhc)
>> + return;
>> +
>> + if (bw != vote_data->curr_freq) {
>
> if (bw == vote_data->curr_freq)
> return;
>
>
>> + for (i = 0; i < BUS_INTERCONNECT_PATHS; i++) {
>> + opp = find_opp_for_freq(msm_host, freq);
>> + if (opp) {
>> + ab[i] = dev_pm_opp_get_bw(opp, &ib[i]);
>> + freq += 1; /* Next Band width vote */
>
> s/Band width/bandwidth/
>
ok.
>> + dev_pm_opp_put(opp);
>> + }
>> + }
>> + pr_debug("%s: freq:%d sdhc_to_ddr ab:%lu ib:%lu cpu_to_sdhc ab:%lu
>> ib:%lu\n",
>> + mmc_hostname(host->mmc), bw, ab[0], ib[0],
>> + ab[1], ib[1]);
>> + ddr_rc = icc_set_bw(vote_data->sdhc_to_ddr, 0, ib[0]);
>> + cpu_rc = icc_set_bw(vote_data->cpu_to_sdhc, 0, ib[1]);
>> + if (ddr_rc || cpu_rc) {
>> + pr_err("%s: icc_set() failed ddr_rc_err:%d cpu_rc_err:%d\n",
>> + mmc_hostname(host->mmc), ddr_rc, cpu_rc);
>> + return;
>> + }
>> + vote_data->curr_freq = bw;
>> + }
>> +}
>> +
>> +/*
>> + * This function registers the device to OPP framework and
>> + * parses few optional parameters from the device tree node.
>> + * Returns NULL bvd pointer on error else a valid bvd pointer.
>> + */
>> +static struct sdhci_msm_bus_vote_data
>> *sdhci_msm_get_bus_vote_data(struct device
>> + *dev, struct sdhci_msm_host *host)
>> +
>> +{
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct sdhci_msm_bus_vote_data *vote_data = NULL;
>> + int ret = 0;
>
> initialization of 'vote_data' and 'ret' is not needed.
>
ok. i will be removing this function and bring all the required to the
caller function
that should address all the comments on this function.
>> +
>> + if (!pdev) {
>> + dev_err(dev, "Null platform device!\n");
>> + return NULL;
>> + }
>
> It's probably safe to assume that the device is a platform device?
>
same as above.
>> + vote_data = devm_kzalloc(dev, sizeof(*vote_data), GFP_KERNEL);
>> + if (!vote_data)
>> + return vote_data;
>
> return ERR_PTR(-ENOMEM); ?
>
>> +
>> + ret = dev_pm_opp_of_add_table(dev);
>> + if (ret) {
>> + if (ret == -ENODEV || ret == -ENODATA) {
>> + dev_dbg(dev, "OPP not found. Skip bus voting!!:%d\n",
>> + ret);
>> + vote_data->skip_bus_bw_voting = true;
>> + } else {
>> + dev_dbg(dev, "OPP regestration failed:%d\n", ret);
>
> s/regestration/registration/
>
ok.
> Depending on the consequences of this failure (e.g. probe() fails) you
> probably want to use dev_warn() or dev_err() here.
>
same as above.
>> + goto err;
>> + }
>> + }
>> +
>> + return vote_data;
>> +err:
>> + devm_kfree(dev, vote_data);
>> + vote_data = NULL;
>
> not needed
>
ok.
>> + return vote_data;
>
> return NULL;
>
>> +}
>> +
>> +/*
>> + * Helper function to register for OPP and interconnect
>> + * frameworks.
>> + */
>> +static int sdhci_msm_bus_register(struct sdhci_msm_host *host,
>> + struct platform_device *pdev)
>> +{
>> + struct sdhci_msm_bus_vote_data *vote_data;
>> + struct device *dev = &pdev->dev;
>> + int ret = 0;
>> +
>> + vote_data = sdhci_msm_get_bus_vote_data(dev, host);
>> + if (!vote_data) {
>> + dev_dbg(&pdev->dev, "Failed to get bus_scale data\n");
>
> In general I'm not convinced about the use of dev_dbg() in the error
> paths. Maybe there is some signal you can use to determine if there
> should be a valid bus scaling information (e.g. some DT property
> exists). If it exists you proceed with obtaining the necessary
> information and complain loudly if something goes wrong, otherwise you
> don't even try to obtain it and omit the debug logs.
>
ok. i will modify accordingly, in my next patch series.

>> + host->bus_vote_data = NULL;
>
> IIUC struct sdhci_msm_host is zero initialized by sdhci_pltfm_init(),
> hence the assignment to NULL is not needed.
>
ok.
>> + return -EINVAL;
>
> Use the error returned by sdhci_msm_get_bus_vote_data().
>
ok. i will address in my next patch set.
>> + }
>> + host->bus_vote_data = vote_data;
>> +
>> + vote_data->sdhc_to_ddr = of_icc_get(&pdev->dev, "sdhc-ddr");
>
> This could be the signal I mentioned above. If this entry does not
> exist it is pointless to proceed. You could check this before
> sdhci_msm_get_bus_vote_data() and abort with a dev_info() message in
> case it doesn't exist. If it exists any error afterwards will be
> reported with dev_err().
>
ok. i will modify the code accordingly in my next patch series.

>> + if (!vote_data->sdhc_to_ddr) {
>> + dev_dbg(&pdev->dev, "DT property for path %s missing\n",
>> + "sdhc-ddr");
>> + return -ENOENT;
>> + } else if (IS_ERR(vote_data->sdhc_to_ddr) {
>> + dev_dbg(&pdev->dev, "(%ld): failed getting %s path\n",
>> + PTR_ERR(vote_data->sdhc_to_ddr), "sdhc-ddr");
>> + ret = PTR_ERR(vote_data->sdhc_to_ddr);
>> + vote_data->sdhc_to_ddr = NULL;
>> + return ret;
>
> if there is an error probe() should probably be aborted. If that's the
> case you can replace the above three lines with 'return
> PTR_ERR(vote_data->sdhc_to_ddr);'
>
True but i added this for more cautious. Any how it is handled as error
probe().
i will address this in my next patch series.


>> + }
>> + vote_data->cpu_to_sdhc = of_icc_get(&pdev->dev, "cpu-sdhc");
>> + if (!vote_data->cpu_to_sdhc) {
>> + dev_dbg(&pdev->dev, "DT property for path %s missing\n",
>> + "cpu_to_sdhc");
>> + return -ENOENT;
>> + } else if (IS_ERR(vote_data->cpu_to_sdhc)) {
>> + dev_dbg(&pdev->dev, "(%ld): failed getting %s path\n",
>> + PTR_ERR(vote_data->cpu_to_sdhc), "cpu-sdhc");
>> + ret = PTR_ERR(vote_data->cpu_to_sdhc);
>> + vote_data->cpu_to_sdhc = NULL;
>> + return ret;
>
> same comment as above
>
ok. i will take care this too.

>> + }
>> + return ret;
>
> no error if we get to this point, hence:
>
> return 0;
>
ok.

>> +}
>> +
>> +static void sdhci_msm_bus_unregister(struct device *dev,
>> + struct sdhci_msm_host *host)
>> +{
>> + struct sdhci_msm_bus_vote_data *vote_data = host->bus_vote_data;
>> +
>> + if (vote_data->skip_bus_bw_voting ||
>> + !vote_data->sdhc_to_ddr ||
>> + !vote_data->cpu_to_sdhc)
>> + return;
>> +
>> + icc_put(vote_data->sdhc_to_ddr);
>> + icc_put(vote_data->cpu_to_sdhc);
>> +}
>> +
>> +#define MSM_MMC_BUS_VOTING_DELAY 200 /* msecs */
>> +
>> +static void sdhci_msm_bus_voting(struct sdhci_host *host, u32 enable)
>
> s/u32/bool/ ?
>
ok.
>> +{
>> + struct mmc_ios *ios = &host->mmc->ios;
>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
>> + unsigned int bw;
>> +
>> + if (msm_host->bus_vote_data->skip_bus_bw_voting)
>> + return;
>> +
>> + if (enable) {
>> + bw = sdhci_get_bw_required(host, ios);
>> + sdhci_msm_bus_set_vote(host, bw);
>> + } else
>> + sdhci_msm_bus_set_vote(host, 0);
>> +}
>> +
>> static const struct sdhci_msm_variant_ops mci_var_ops = {
>> .msm_readl_relaxed = sdhci_msm_mci_variant_readl_relaxed,
>> .msm_writel_relaxed = sdhci_msm_mci_variant_writel_relaxed,
>> @@ -1845,11 +2072,20 @@ static int sdhci_msm_probe(struct
>> platform_device *pdev)
>> dev_warn(&pdev->dev, "TCXO clk not present (%d)\n", ret);
>> }
>>
>> + ret = sdhci_msm_bus_register(msm_host, pdev);
>> + if (ret && msm_host->bus_vote_data &&
>> + !msm_host->bus_vote_data->skip_bus_bw_voting) {
>> + dev_err(&pdev->dev, "Bus registration failed (%d)\n", ret);
>> + goto clk_disable;
>> + }
>> +
>> + sdhci_msm_bus_voting(host, 1);
>
> s/1/true/
>
ok.
>> +
>> if (!msm_host->mci_removed) {
>> msm_host->core_mem = devm_platform_ioremap_resource(pdev, 1);
>> if (IS_ERR(msm_host->core_mem)) {
>> ret = PTR_ERR(msm_host->core_mem);
>> - goto clk_disable;
>> + goto bus_unregister;
>> }
>> }
>>
>> @@ -1924,7 +2160,7 @@ static int sdhci_msm_probe(struct
>> platform_device *pdev)
>> msm_host->pwr_irq = platform_get_irq_byname(pdev, "pwr_irq");
>> if (msm_host->pwr_irq < 0) {
>> ret = msm_host->pwr_irq;
>> - goto clk_disable;
>> + goto bus_unregister;
>> }
>>
>> sdhci_msm_init_pwr_irq_wait(msm_host);
>> @@ -1937,7 +2173,7 @@ static int sdhci_msm_probe(struct
>> platform_device *pdev)
>> dev_name(&pdev->dev), host);
>> if (ret) {
>> dev_err(&pdev->dev, "Request IRQ failed (%d)\n", ret);
>> - goto clk_disable;
>> + goto bus_unregister;
>> }
>>
>> pm_runtime_get_noresume(&pdev->dev);
>> @@ -1962,6 +2198,9 @@ static int sdhci_msm_probe(struct
>> platform_device *pdev)
>> pm_runtime_disable(&pdev->dev);
>> pm_runtime_set_suspended(&pdev->dev);
>> pm_runtime_put_noidle(&pdev->dev);
>> +bus_unregister:
>> + sdhci_msm_bus_voting(host, 0);
>
> s/0/false/
>
ok.
>> + sdhci_msm_bus_unregister(&pdev->dev, msm_host);
>> clk_disable:
>> clk_bulk_disable_unprepare(ARRAY_SIZE(msm_host->bulk_clks),
>> msm_host->bulk_clks);
>> @@ -1991,6 +2230,9 @@ static int sdhci_msm_remove(struct
>> platform_device *pdev)
>> msm_host->bulk_clks);
>> if (!IS_ERR(msm_host->bus_clk))
>> clk_disable_unprepare(msm_host->bus_clk);
>> +
>> + sdhci_msm_bus_voting(host, 0);
>
> s/0/false/
>
ok.
>> + sdhci_msm_bus_unregister(&pdev->dev, msm_host);
>> sdhci_pltfm_free(pdev);
>> return 0;
>> }
>> @@ -2003,7 +2245,7 @@ static __maybe_unused int
>> sdhci_msm_runtime_suspend(struct device *dev)
>>
>> clk_bulk_disable_unprepare(ARRAY_SIZE(msm_host->bulk_clks),
>> msm_host->bulk_clks);
>> -
>> + sdhci_msm_bus_voting(host, 0);
>
> s/0/false/
>
ok.
>> return 0;
>> }
>>
>> @@ -2025,6 +2267,7 @@ static __maybe_unused int
>> sdhci_msm_runtime_resume(struct device *dev)
>> if (msm_host->restore_dll_config && msm_host->clk_rate)
>> return sdhci_msm_restore_sdr_dll_config(host);
>>
>> + sdhci_msm_bus_voting(host, 1);
>
> s/0/true/
>
ok. i will address all these in my next patch series.
> Thanks
>
> Matthias

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