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Message-ID: <1905d25f-d16d-50b1-54b0-35807d801a12@intel.com>
Date: Mon, 19 Mar 2018 12:00:15 +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 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@...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.
>
> 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.
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