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

[Adrian Hunter]

This is a multi-part message in MIME format.On 20/03/18 11:48, Kishon Vijay Abraham I wrote:
> Hi Adrian,
> 
> On Monday 19 March 2018 03:49 PM, Kishon Vijay Abraham I wrote:
>> Hi Adrian,
>>
>> On Monday 19 March 2018 03:30 PM, Adrian Hunter wrote:
>>> On 19/03/18 11:20, Kishon Vijay Abraham I wrote:
>>>> Hi Adrian,
>>>>
>>>> On Friday 16 March 2018 07:51 PM, Adrian Hunter wrote:
>>>>> On 16/03/18 08:29, Kishon Vijay Abraham I wrote:
>>>>>> 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@xxxxxx>
>>>>>>>> ---
>>>>>>>>  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?
>>>>>
>>>>> Yes, but I was thinking you would only calculate when it was needed.
>>>>
>>>> I feel since we would have anyways calculated data_timeout, we should use that
>>>> instead unless you see a problem with that.
>>>
>>> I would prefer not to calculate data_timeout when a hardware timeout is
>>> being used.
>>>
>>
>> That differs from what I had thought. This patch tries to program a relatively
>> accurate SW timeout value (for data_timer) irrespective of whether hardware
>> timeout is used or not. This only tries to change the 10 Sec SW timeout value
>> programmed for all data transfer commands.
> 
> IMHO since we calculate the worst case timeout value we should be using that
> for all cases where we are able to calculate the timeout value so that we don't
> give a too high or too low timeout value. Let me know If this sounds okay to you.

I don't want to do the calculation for drivers that don't need it.

How about the 3 patches attached