lkml.org 
[lkml]   [2019]   [Dec]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 2/7] mmc: sdhci: add support for using external DMA devices
From
Date
Hi Adrian,

On 12/12/19 6:25 pm, Adrian Hunter wrote:
> On 10/12/19 11:51 am, Faiz Abbas wrote:
>> From: Chunyan Zhang <zhang.chunyan@linaro.org>
>>
>> Some standard SD host controllers can support both external dma
>> controllers as well as ADMA/SDMA in which the SD host controller
>> acts as DMA master. TI's omap controller is the case as an example.
>>
>> Currently the generic SDHCI code supports ADMA/SDMA integrated in
>> the host controller but does not have any support for external DMA
>> controllers implemented using dmaengine, meaning that custom code is
>> needed for any systems that use an external DMA controller with SDHCI.
>>
>> Fixes by Faiz Abbas <faiz_abbas@ti.com>:
>> 1. Map scatterlists before dmaengine_prep_slave_sg()
>> 2. Use dma_async() functions inside of the send_command() path and call
>> terminate_sync() in non-atomic context in case of an error.
>>
>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
>> Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
>> ---
...
>> {
>> @@ -1379,12 +1562,19 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>> }
>>
>> host->cmd = cmd;
>> + host->data_timeout = 0;
>> if (sdhci_data_line_cmd(cmd)) {
>> WARN_ON(host->data_cmd);
>> host->data_cmd = cmd;
>> + sdhci_set_timeout(host, cmd);
>> }
>>
>> - sdhci_prepare_data(host, cmd);
>> + if (cmd->data) {
>> + if (host->use_external_dma)
>> + sdhci_external_dma_prepare_data(host, cmd);
>> + else
>> + sdhci_prepare_data(host, cmd);
>> + }
>
> Please make the 3 changes above and the corresponding changes
> sdhci_prepare_data into a separate patch i.e.

Ok. And I agree with all your style change requests above this. Will fix
in v4.

>> @@ -2652,6 +2845,18 @@ static bool sdhci_request_done(struct sdhci_host *host)
>> if (host->flags & SDHCI_REQ_USE_DMA) {
>> struct mmc_data *data = mrq->data;
>>
>> + spin_unlock_irqrestore(&host->lock, flags);
>> +
>> + /* Terminate and synchronize dma in case of an error */
>> + if (data && (mrq->cmd->error || data->error) &&
>> + host->use_external_dma) {
>> + struct dma_chan *chan = sdhci_external_dma_channel(host,
>> + data);
>> + dmaengine_terminate_sync(chan);
>> + }
>> +
>> + spin_lock_irqsave(&host->lock, flags);
>> +
>
> Need to take the mrq out of mrqs_done[] to ensure it is not processed again,
> and put it back again to be consistent with the remaining code. Also put
> host->use_external_dma as the first condition i.e.
>
> if (host->use_external_dma && data &&
> (mrq->cmd->error || data->error)) {
> struct dma_chan *chan = sdhci_external_dma_channel(host, data);
>
> host->mrqs_done[i] = NULL;
> spin_unlock_irqrestore(&host->lock, flags);
> dmaengine_terminate_sync(chan);
> spin_lock_irqsave(&host->lock, flags);
> sdhci_set_mrq_done(host, mrq);
> }
>
> where sdhci_set_mrq_done() is factored out from __sdhci_finish_mrq() i.e.
>
> static void sdhci_set_mrq_done(struct sdhci_host *host, struct mmc_request *mrq)
> {
> int i;
>
> for (i = 0; i < SDHCI_MAX_MRQS; i++) {
> if (host->mrqs_done[i] == mrq) {
> WARN_ON(1);
> return;
> }
> }
>
> for (i = 0; i < SDHCI_MAX_MRQS; i++) {
> if (!host->mrqs_done[i]) {
> host->mrqs_done[i] = mrq;
> break;
> }
> }
>
> WARN_ON(i >= SDHCI_MAX_MRQS);
> }
>
> sdhci_set_mrq_done() can be made in the refactoring patch.
Haven't we already done the sdhci_set_mrq_done() part in
__sdhci_finish_mrq()?

We are picking up an already "done" mrq, looking at whether it had any
error and then sychronizing with external dma. Or at least that is my
understanding.

>
>> if (data && data->host_cookie == COOKIE_MAPPED) {
>> if (host->bounce_buffer) {
>> /*
>> @@ -3758,12 +3963,28 @@ int sdhci_setup_host(struct sdhci_host *host)
>> mmc_hostname(mmc), host->version);
>> }
>>
>> - if (host->quirks & SDHCI_QUIRK_FORCE_DMA)
>> + if (host->use_external_dma) {
>> + ret = sdhci_external_dma_init(host);
>> + if (ret == -EPROBE_DEFER)
>> + goto unreg;
>> +
>> + /*
>> + * Fall back to use the DMA/PIO integrated in standard SDHCI
>> + * instead of external DMA devices.
>> + */
>> + if (ret)
>> + sdhci_switch_external_dma(host, false);
>> + }
>> +
>> + if (host->quirks & SDHCI_QUIRK_FORCE_DMA) {
>> host->flags |= SDHCI_USE_SDMA;
>> - else if (!(host->caps & SDHCI_CAN_DO_SDMA))
>> + } else if (!(host->caps & SDHCI_CAN_DO_SDMA)) {
>> DBG("Controller doesn't have SDMA capability\n");
>> - else
>> + } else if (host->use_external_dma) {
>> + /* Using dma-names to detect external dma capability */
>
> What is this change for? Do you expect for SDHCI_USE_SDMA and
> SDHCI_USE_ADMA flags to be clear?

Yes. Today the code enables SDMA by default (in the else part below
this). I want it to not enable SDMA in the external dma case.

Thanks,
Faiz

\
 
 \ /
  Last update: 2019-12-16 09:27    [W:0.040 / U:10.796 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site