From: vbadigan@codeaurora.org
To: Douglas Anderson <dianders@chromium.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Andy Gross <agross@kernel.org>,
Asutosh Das <asutoshd@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Chris Ball <chris@printf.net>, Georgi Djakov <gdjakov@mm-sol.com>,
Venkat Gopalakrishnan <venkatg@codeaurora.org>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mmc@vger.kernel.org
Subject: Re: [PATCH] mmc: sdhci-msm: Add retries when all tuning phases are found valid
Date: Fri, 28 Aug 2020 18:12:34 +0530 [thread overview]
Message-ID: <f986b516b37dbb788330334468af07cf@codeaurora.org> (raw)
In-Reply-To: <20200827075809.1.If179abf5ecb67c963494db79c3bc4247d987419b@changeid>
On 2020-08-27 20:28, Douglas Anderson wrote:
> As the comments in this patch say, if we tune and find all phases are
> valid it's _almost_ as bad as no phases being found valid. Probably
> all phases are not really reliable but we didn't detect where the
> unreliable place is. That means we'll essentially be guessing and
> hoping we get a good phase.
>
> This is not just a problem in theory. It was causing real problems on
> a real board. On that board, most often phase 10 is found as the only
> invalid phase, though sometimes 10 and 11 are invalid and sometimes
> just 11. Some percentage of the time, however, all phases are found
> to be valid. When this happens, the current logic will decide to use
> phase 11. Since phase 11 is sometimes found to be invalid, this is a
> bad choice. Sure enough, when phase 11 is picked we often get mmc
> errors later in boot.
>
> I have seen cases where all phases were found to be valid 3 times in a
> row, so increase the retry count to 10 just to be extra sure.
>
> Fixes: 415b5a75da43 ("mmc: sdhci-msm: Add platform_execute_tuning
> implementation")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
Thanks for adding this logic.
Reviewed-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
> drivers/mmc/host/sdhci-msm.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c
> b/drivers/mmc/host/sdhci-msm.c
> index b7e47107a31a..1b78106681e0 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -1165,7 +1165,7 @@ static void sdhci_msm_set_cdr(struct sdhci_host
> *host, bool enable)
> static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode)
> {
> struct sdhci_host *host = mmc_priv(mmc);
> - int tuning_seq_cnt = 3;
> + int tuning_seq_cnt = 10;
> u8 phase, tuned_phases[16], tuned_phase_cnt = 0;
> int rc;
> struct mmc_ios ios = host->mmc->ios;
> @@ -1221,6 +1221,22 @@ static int sdhci_msm_execute_tuning(struct
> mmc_host *mmc, u32 opcode)
> } while (++phase < ARRAY_SIZE(tuned_phases));
>
> if (tuned_phase_cnt) {
> + if (tuned_phase_cnt == ARRAY_SIZE(tuned_phases)) {
> + /*
> + * All phases valid is _almost_ as bad as no phases
> + * valid. Probably all phases are not really reliable
> + * but we didn't detect where the unreliable place is.
> + * That means we'll essentially be guessing and hoping
> + * we get a good phase. Better to try a few times.
> + */
> + dev_dbg(mmc_dev(mmc), "%s: All phases valid; try again\n",
> + mmc_hostname(mmc));
> + if (--tuning_seq_cnt) {
> + tuned_phase_cnt = 0;
> + goto retry;
> + }
> + }
> +
> rc = msm_find_most_appropriate_phase(host, tuned_phases,
> tuned_phase_cnt);
> if (rc < 0)
next prev parent reply other threads:[~2020-08-28 12:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 14:58 [PATCH] mmc: sdhci-msm: Add retries when all tuning phases are found valid Douglas Anderson
2020-08-28 12:42 ` vbadigan [this message]
2020-08-31 14:14 ` Adrian Hunter
2020-09-02 9:03 ` Ulf Hansson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f986b516b37dbb788330334468af07cf@codeaurora.org \
--to=vbadigan@codeaurora.org \
--cc=adrian.hunter@intel.com \
--cc=agross@kernel.org \
--cc=asutoshd@codeaurora.org \
--cc=bjorn.andersson@linaro.org \
--cc=chris@printf.net \
--cc=dianders@chromium.org \
--cc=gdjakov@mm-sol.com \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=ulf.hansson@linaro.org \
--cc=venkatg@codeaurora.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).