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Message-ID: <47ed0a0b-dfaa-40e1-825a-9a42e66b887e@intel.com>
Date: Fri, 23 Aug 2024 16:45:41 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Judith Mendez <jm@...com>
Cc: Adrian Hunter <adrian.hunter@...el.com>, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mmc: sdhci_am654: Add retry tuning
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
> ---
> 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.
>
> #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.
> +}
>
> - /* 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);
> +
> + 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.
> +
> + 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?
> host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>
> pm_runtime_get_noresume(dev);
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