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Message-ID: <feee18cc-e75b-49d9-ac09-a0afbb0b00ca@ti.com>
Date: Fri, 23 Aug 2024 15:44:00 -0500
From: Judith Mendez <jm@...com>
To: Adrian Hunter <adrian.hunter@...el.com>
CC: <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] mmc: sdhci_am654: Add retry tuning
Hi Adrian,
On 8/23/24 8:45 AM, Adrian Hunter wrote:
> On 21/08/24 22:24, Judith Mendez wrote:
>> Add retry tuning up to 10 times if we fail to find
>> a failing region or no passing itapdly. This is
>> necessary since some eMMC has been observed to never
>> find a failing itapdly on the first couple of tuning
>> iterations, but eventually does. It has been observed that
>> the tuning algorithm does not need to loop more than 10
>> times before finding a failing itapdly.
>>
>> Signed-off-by: Judith Mendez <jm@...com>
>
> Seems to have compile errors. Looks like 'dev' lines belong in
> next patch.
>
> drivers/mmc/host/sdhci_am654.c: In function ‘sdhci_am654_calculate_itap’:
> drivers/mmc/host/sdhci_am654.c:453:24: error: unused variable ‘dev’ [-Werror=unused-variable]
> 453 | struct device *dev = mmc_dev(host->mmc);
> | ^~~
> drivers/mmc/host/sdhci_am654.c: In function ‘sdhci_am654_do_tuning’:
> drivers/mmc/host/sdhci_am654.c:508:24: error: unused variable ‘dev’ [-Werror=unused-variable]
> 508 | struct device *dev = mmc_dev(host->mmc);
> | ^~~
> drivers/mmc/host/sdhci_am654.c: In function ‘sdhci_am654_platform_execute_tuning’:
> drivers/mmc/host/sdhci_am654.c:553:24: error: unused variable ‘dev’ [-Werror=unused-variable]
> 553 | struct device *dev = mmc_dev(host->mmc);
> | ^~~
> cc1: all warnings being treated as errors
ok, will move to second patch.
>
>> ---
>> Changes since v1:
>> - Change logic in patch 1/2 from using recursive aproach
>> to calling a function iteratively for retuning
>> ---
>> drivers/mmc/host/sdhci_am654.c | 54 ++++++++++++++++++++++++++--------
>> 1 file changed, 42 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>> index 64e10f7c9faa3..612f29fd7dfef 100644
>> --- a/drivers/mmc/host/sdhci_am654.c
>> +++ b/drivers/mmc/host/sdhci_am654.c
>> @@ -86,6 +86,7 @@
>>
>> #define CLOCK_TOO_SLOW_HZ 50000000
>> #define SDHCI_AM654_AUTOSUSPEND_DELAY -1
>> +#define RETRY_TUNING_MAX 10
>>
>> /* Command Queue Host Controller Interface Base address */
>> #define SDHCI_AM654_CQE_BASE_ADDR 0x200
>> @@ -151,6 +152,7 @@ struct sdhci_am654_data {
>> u32 flags;
>> u32 quirks;
>> bool dll_enable;
>> + u32 tuning_loop;
>
> Could use a comment explaining tuning_loop usage.
Sure no problem, will add.
>
>>
>> #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>> };
>> @@ -453,12 +455,14 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
>> int prev_fail_end = -1;
>> u8 i;
>>
>> - if (!num_fails)
>> - return ITAPDLY_LAST_INDEX >> 1;
>> + if (!num_fails) {
>> + /* Retry tuning */
>> + return -1;
>> + }
>>
>> if (fail_window->length == ITAPDLY_LENGTH) {
>> - dev_err(dev, "No passing ITAPDLY, return 0\n");
>> - return 0;
>> + /* Retry tuning */
>> + return -1;
>> }
>>
>> first_fail_start = fail_window->start;
>> @@ -494,16 +498,18 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
>> return (itap > ITAPDLY_LAST_INDEX) ? ITAPDLY_LAST_INDEX >> 1 : itap;
>> }
>>
>> -static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>> - u32 opcode)
>> +static int sdhci_am654_do_tuning(struct sdhci_host *host,
>> + u32 opcode)
>> {
>> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>> unsigned char timing = host->mmc->ios.timing;
>> struct window fail_window[ITAPDLY_LENGTH];
>> + struct device *dev = mmc_dev(host->mmc);
>> u8 curr_pass, itap;
>> u8 fail_index = 0;
>> u8 prev_pass = 1;
>> + int ret = 0;
>>
>> memset(fail_window, 0, sizeof(fail_window));
>>
>> @@ -532,15 +538,38 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>> if (fail_window[fail_index].length != 0)
>> fail_index++;
>>
>> - itap = sdhci_am654_calculate_itap(host, fail_window, fail_index,
>> - sdhci_am654->dll_enable);
>> + ret = sdhci_am654_calculate_itap(host, fail_window, fail_index,
>> + sdhci_am654->dll_enable);
>>
>> - sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
>> + return ret;
>
> Kernel style is to return directly i.e.
>
> return sdhci_am654_calculate_itap(host, fail_window, fail_index, sdhci_am654->dll_enable);
>
> then don't need ret.
Will fix.
>
>> +}
>>
>> - /* Save ITAPDLY */
>> - sdhci_am654->itap_del_sel[timing] = itap;
>> +static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>> + u32 opcode)
>> +{
>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>> + struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>> + unsigned char timing = host->mmc->ios.timing;
>> + struct device *dev = mmc_dev(host->mmc);
>> + int itapdly;
>> + int ret = 0;
>>
>> - return 0;
>> + itapdly = sdhci_am654_do_tuning(host, opcode);
>> +
>> + while (sdhci_am654->tuning_loop < RETRY_TUNING_MAX && itapdly < 0) {
>> + sdhci_am654->tuning_loop++;
>> + itapdly = sdhci_am654_do_tuning(host, opcode);
>> + }
>
> Better to try to have sdhci_am654_do_tuning() appear only once
> e.g. something like:
>
> do {
> itapdly = sdhci_am654_do_tuning(host, opcode);
> if (itapdly >= 0)
> break;
> } while (++sdhci_am654->tuning_loop < RETRY_TUNING_MAX);
>
I generally do not like using do while loops, but in this case
it is the more appropriate solution, thanks, will fix.
>
>> +
>> + if (itapdly >= 0) {
>> + sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
>> + /* Save ITAPDLY */
>> + sdhci_am654->itap_del_sel[timing] = itapdly;
>> + } else {
>> + ret = -1;
>> + }
>
> It is easier to read if the error path is separate e.g.
>
> if (itapdly < 0)
> return -1;
>
> sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
> /* Save ITAPDLY */
> sdhci_am654->itap_del_sel[timing] = itapdly;
>
> return 0;
>
> Doesn't need ret then either.
ok, yes this looks cleaner, thanks.
>
>> +
>> + return ret;
>> }
>>
>> static const struct sdhci_ops sdhci_am654_ops = {
>> @@ -908,6 +937,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>> goto err_pltfm_free;
>> }
>>
>> + sdhci_am654->tuning_loop = 0;
>
> It is a bit arbitrary having this at probe time. Something like
> putting it in an mmc card_init callback might make more sense?
Sure I can move this. Thanks for reviewing!
~ Judith
>
>> host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>>
>> pm_runtime_get_noresume(dev);
>
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