linux-kernel - Re: [PATCH V2] mmc: sdhci-msm: Disable CQE during SDHC reset

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Date:   Wed, 4 Mar 2020 16:10:18 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Veerabhadrarao Badiganti <vbadigan@...eaurora.org>,
        ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH V2] mmc: sdhci-msm: Disable CQE during SDHC reset

On 4/03/20 3:10 pm, Veerabhadrarao Badiganti wrote:
> Hi Adrian
> 
> On 3/4/2020 5:58 PM, Adrian Hunter wrote:
>> On 4/03/20 1:54 pm, Veerabhadrarao Badiganti wrote:
>>> When SDHC gets reset (E.g. in suspend path), CQE also gets reset
>>> and goes to disable state. But s/w state still points it as CQE
>>> is in enabled state. Since s/w and h/w states goes out of sync,
>>> it results in s/w request timeout for subsequent CQE requests.
>>>
>>> To synchronize CQE s/w and h/w state during SDHC reset,
>>> explicitly disable CQE after reset.
>> Shouldn't you be calling cqhci_suspend() / cqhci_resume() in the suspend and
>> resume paths?
> 
> This issue is seen during mmc runtime suspend.  I can add it
> sdhci_msm_runtime_suspend
> 
> but sdhci_msm runtime delay is aggressive, its 50ms. It may get invoked very
> frequently.
> 
> So Im of the opinion that disabling CQE very often from platform runtime
> suspend is overkill.

It doesn't look like sdhci-msm calls any sdhci.c pm ops, so how does SDHC
get reset?

> 
>>> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
>>> ---
>>> Changes since V1:
>>>     - Disable CQE only when SDHC undergoes s/w reset for all.
>>> ---
>>>   drivers/mmc/host/sdhci-msm.c | 9 ++++++++-
>>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
>>> index 53b79ee..75929d3 100644
>>> --- a/drivers/mmc/host/sdhci-msm.c
>>> +++ b/drivers/mmc/host/sdhci-msm.c
>>> @@ -1823,6 +1823,13 @@ static void sdhci_msm_set_regulator_caps(struct
>>> sdhci_msm_host *msm_host)
>>>       pr_debug("%s: supported caps: 0x%08x\n", mmc_hostname(mmc), caps);
>>>   }
>>>   +static void sdhci_msm_reset(struct sdhci_host *host, u8 mask)
>>> +{
>>> +    sdhci_reset(host, mask);
>>> +    if ((host->mmc->caps2 & MMC_CAP2_CQE) && (mask & SDHCI_RESET_ALL))
>>> +        cqhci_suspend(host->mmc);
>>> +}
>>> +
>>>   static const struct sdhci_msm_variant_ops mci_var_ops = {
>>>       .msm_readl_relaxed = sdhci_msm_mci_variant_readl_relaxed,
>>>       .msm_writel_relaxed = sdhci_msm_mci_variant_writel_relaxed,
>>> @@ -1861,7 +1868,7 @@ static void sdhci_msm_set_regulator_caps(struct
>>> sdhci_msm_host *msm_host)
>>>   MODULE_DEVICE_TABLE(of, sdhci_msm_dt_match);
>>>     static const struct sdhci_ops sdhci_msm_ops = {
>>> -    .reset = sdhci_reset,
>>> +    .reset = sdhci_msm_reset,
>>>       .set_clock = sdhci_msm_set_clock,
>>>       .get_min_clock = sdhci_msm_get_min_clock,
>>>       .get_max_clock = sdhci_msm_get_max_clock,
>>>