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SubjectRe: [PATCH v3 07/11] mmc: sdhci: Program a relatively accurate SW timeout value
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Hi,

On Thursday 15 March 2018 06:43 PM, Adrian Hunter wrote:
> On 07/03/18 15:20, Kishon Vijay Abraham I wrote:
>> sdhci has a 10 second timeout to catch devices that stop responding.
>> Instead of programming 10 second arbitrary value, calculate the total time
>> it would take for the entire transfer to happen and program the timeout
>> value accordingly.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
>> ---
>> drivers/mmc/host/sdhci.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
>> drivers/mmc/host/sdhci.h | 10 ++++++++++
>> 2 files changed, 50 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 1dd117cbeb6e..baab67bfa39b 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -709,6 +709,36 @@ static u32 sdhci_sdma_address(struct sdhci_host *host)
>> return sg_dma_address(host->data->sg);
>> }
>>
>> +static void sdhci_calc_sw_timeout(struct sdhci_host *host,
>> + struct mmc_command *cmd,
>> + unsigned int target_timeout)
>> +{
>> + struct mmc_data *data = cmd->data;
>> + struct mmc_host *mmc = host->mmc;
>> + u64 transfer_time;
>> + struct mmc_ios *ios = &mmc->ios;
>> + unsigned char bus_width = 1 << ios->bus_width;
>> + unsigned int blksz;
>> + unsigned int freq;
>> +
>> + if (data) {
>> + blksz = data->blksz;
>> + freq = host->mmc->actual_clock ? : host->clock;
>> + transfer_time = (u64)blksz * NSEC_PER_SEC * (8 / bus_width);
>> + do_div(transfer_time, freq);
>> + /* multiply by '2' to account for any unknowns */
>> + transfer_time = transfer_time * 2;
>> + /* calculate timeout for the entire data */
>> + host->data_timeout = (data->blocks * ((target_timeout *
>> + NSEC_PER_USEC) +
>> + transfer_time));
>
> (target_timeout * NSEC_PER_USEC) might be 32-bit and therefore overflow
> for timeouts greater than about 4 seconds.
>
>> + } else {
>> + host->data_timeout = (u64)target_timeout * NSEC_PER_USEC;
>> + }
>> +
>> + host->data_timeout += MMC_CMD_TRANSFER_TIME;
>
> Need to allow for target_timeout == 0 so:
>
> if (host->data_timeout)
> host->data_timeout += MMC_CMD_TRANSFER_TIME;
>
>> +}
>> +
>> static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>> {
>> u8 count;
>> @@ -766,6 +796,7 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>> if (count >= 0xF)
>> break;
>> }
>> + sdhci_calc_sw_timeout(host, cmd, target_timeout);
>
> If you make the changes I suggest for patch 6, then this would
> move sdhci_calc_sw_timeout() into sdhci_set_timeout().
>
> I suggest you factor out the target_timeout calculation e.g.
>
> static unsigned int sdhci_target_timeout(struct sdhci_host *host,
> struct mmc_command *cmd,
> struct mmc_data *data)
> {
> unsigned int target_timeout;
>
> /* timeout in us */
> if (!data)
> target_timeout = cmd->busy_timeout * 1000;
> else {
> target_timeout = DIV_ROUND_UP(data->timeout_ns, 1000);
> if (host->clock && data->timeout_clks) {
> unsigned long long val;
>
> /*
> * data->timeout_clks is in units of clock cycles.
> * host->clock is in Hz. target_timeout is in us.
> * Hence, us = 1000000 * cycles / Hz. Round up.
> */
> val = 1000000ULL * data->timeout_clks;
> if (do_div(val, host->clock))
> target_timeout++;
> target_timeout += val;
> }
> }
>
> return target_timeout;
> }
>
> And call it from sdhci_calc_sw_timeout()
>
>>
>> return count;
>> }
>> @@ -1175,13 +1206,6 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>> mdelay(1);
>> }
>>
>> - timeout = jiffies;
>> - if (!cmd->data && cmd->busy_timeout > 9000)
>> - timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
>> - else
>> - timeout += 10 * HZ;
>> - sdhci_mod_timer(host, cmd->mrq, timeout);
>> -
>> host->cmd = cmd;
>> if (sdhci_data_line_cmd(cmd)) {
>> WARN_ON(host->data_cmd);
>> @@ -1221,6 +1245,15 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
>> cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200)
>> flags |= SDHCI_CMD_DATA;
>>
>> + timeout = jiffies;
>> + if (host->data_timeout > 0) {
>
> This can be just:
>
> if (host->data_timeout) {
>
>> + timeout += nsecs_to_jiffies(host->data_timeout);
>> + host->data_timeout = 0;
>
> It would be better to initialize host->data_timeout = 0 at the top of
> sdhci_prepare_data().
>
> Also still need:
>
> else if (!cmd->data && cmd->busy_timeout > 9000) {
> timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;

sdhci_calc_sw_timeout should have calculated the timeout for this case too no?

Thanks
Kishon

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