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

[Adrian Hunter <adrian.hunter@intel.com>]

On 4/03/20 6:50 pm, Veerabhadrarao Badiganti wrote:
> 
> On 3/4/2020 7:40 PM, Adrian Hunter wrote:
>> 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?
> 
> With MMC_CAP_AGGRESSIVE_PM flag enabled, it getting called from
> mmc_runtime_suspend()
> 
> Below is the call stack()
> 
>    sdhci_reset
>   sdhci_do_reset
>   sdhci_init
>   sdhci_set_ios
>   mmc_set_initial_state
>   mmc_power_off
>  _mmc_suspend
>   mmc_runtime_suspend
> 

OK, cqhci_suspend does the right thing, but it is not an
appropriate function for this.  I suggest introducing
cqhci_deactivate() as below.

From: Adrian Hunter <adrian.hunter@intel.com>
Date: Thu, 5 Mar 2020 10:42:09 +0200
Subject: [PATCH] mmc: cqhci: Add cqhci_deactivate()

Host controllers can reset CQHCI either directly or as a consequence of
host controller reset. Add cqhci_deactivate() which puts the CQHCI
driver into a state that is consistent with that.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/host/cqhci.c | 6 +++---
 drivers/mmc/host/cqhci.h | 5 ++++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/cqhci.c b/drivers/mmc/host/cqhci.c
index e2ea2c4b6b94..d8d024a1682b 100644
--- a/drivers/mmc/host/cqhci.c
+++ b/drivers/mmc/host/cqhci.c
@@ -298,16 +298,16 @@ static void __cqhci_disable(struct cqhci_host *cq_host)
 	cq_host->activated = false;
 }
 
-int cqhci_suspend(struct mmc_host *mmc)
+int cqhci_deactivate(struct mmc_host *mmc)
 {
 	struct cqhci_host *cq_host = mmc->cqe_private;
 
-	if (cq_host->enabled)
+	if (cq_host->enabled && cq_host->activated)
 		__cqhci_disable(cq_host);
 
 	return 0;
 }
-EXPORT_SYMBOL(cqhci_suspend);
+EXPORT_SYMBOL(cqhci_deactivate);
 
 int cqhci_resume(struct mmc_host *mmc)
 {
diff --git a/drivers/mmc/host/cqhci.h b/drivers/mmc/host/cqhci.h
index def76e9b5cac..8648846a0213 100644
--- a/drivers/mmc/host/cqhci.h
+++ b/drivers/mmc/host/cqhci.h
@@ -230,7 +230,10 @@ irqreturn_t cqhci_irq(struct mmc_host *mmc, u32 intmask, int cmd_error,
 		      int data_error);
 int cqhci_init(struct cqhci_host *cq_host, struct mmc_host *mmc, bool dma64);
 struct cqhci_host *cqhci_pltfm_init(struct platform_device *pdev);
-int cqhci_suspend(struct mmc_host *mmc);
+static inline int cqhci_suspend(struct mmc_host *mmc)
+{
+	return cqhci_deactivate(mmc);
+}
 int cqhci_resume(struct mmc_host *mmc);
 
 #endif
-- 
2.17.1


Also, it would be more logical to deactivate prior to the reset i.e.

+    if ((host->mmc->caps2 & MMC_CAP2_CQE) && (mask & SDHCI_RESET_ALL))
+        cqhci_deactivate(host->mmc);
+    sdhci_reset(host, mask);


Also, other drivers using cqhci, should probably do this too, although
some of them do not reset cqhci with sdhci so perhaps do not need to.

>>>>> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.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,
>>>>>