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

[Adrian Hunter]

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.