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Message-ID: <49210daa-b593-4b34-abf5-be81580723bc@intel.com>
Date: Fri, 16 Mar 2018 16:21:08 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Kishon Vijay Abraham I <kishon@...com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Tony Lindgren <tony@...mide.com>
Cc: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Russell King <linux@...linux.org.uk>,
linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 07/11] mmc: sdhci: Program a relatively accurate SW
timeout value
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@...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?
Yes, but I was thinking you would only calculate when it was needed.
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