linux-kernel - Re: [PATCH v3 6/7] mmc: sdhci_am654: Fix SDHCI_RESET

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Date:   Wed, 26 Oct 2022 08:36:48 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Brian Norris <briannorris@...omium.org>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        linux-mmc@...r.kernel.org, Al Cooper <alcooperx@...il.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        NXP Linux Team <linux-imx@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-kernel@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-arm-msm@...r.kernel.org, Haibo Chen <haibo.chen@....com>,
        Andy Gross <agross@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Faiz Abbas <faiz_abbas@...com>,
        Jonathan Hunter <jonathanh@...dia.com>
Subject: Re: [PATCH v3 6/7] mmc: sdhci_am654: Fix SDHCI_RESET_ALL for CQHCI

On 26/10/22 01:26, Brian Norris wrote:
> On Tue, Oct 25, 2022 at 02:53:46PM -0700, Florian Fainelli wrote:
>> On 10/25/22 14:45, Brian Norris wrote:
>>> On Tue, Oct 25, 2022 at 04:10:44PM +0300, Adrian Hunter wrote:
>>>> On 24/10/22 20:55, Brian Norris wrote:
>>>>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>>>>> index 8f1023480e12..6a282c7a221e 100644
>>>>> --- a/drivers/mmc/host/sdhci_am654.c
>>>>> +++ b/drivers/mmc/host/sdhci_am654.c
>>>
>>>>> @@ -378,7 +379,7 @@ static void sdhci_am654_reset(struct sdhci_host *host, u8 mask)
>>>>>   	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>>>>   	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>>>>> -	sdhci_reset(host, mask);
>>>>> +	sdhci_and_cqhci_reset(host, mask);
>>>>>   	if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_FORCE_CDTEST) {
>>>>>   		ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
>>>>
>>>> What about sdhci_reset in sdhci_am654_ops ?
>>>
>>> Oops, I think you caught a big fallacy in some of my patches: I assumed
>>> there was a single reset() implementation in a given driver (an unwise
>>> assumption, I realize). I see at least sdhci-brcmstb.c also has several
>>> variant ops that call sdhci_reset(), and I should probably convert them
>>> too.

I checked and found only sdhci_am654_ops

>>
>> You got it right for sdhci-brcmstb.c because "supports-cqe" which gates the
>> enabling of CQE can only be found with the "brcm,bcm7216-sdhci" compatible
>> which implies using brcmstb_reset().
> 
> I don't see any in-tree device trees for these chips (which is OK), and
> that's not what the Documentation/ says, and AFAICT nothing in the
> driver is limiting other variants from specifying the "supports-cqe"
> flag in their (out-of-tree) device tree. The closest thing I see is that
> an *example* in brcm,sdhci-brcmstb.yaml shows "supports-cqe" only on
> brcm,bcm7216-sdhci -- but an example is not a binding agreement. Am I
> missing something?

It was mentioned in the patch from the Fixes tag.

> 
> Now of course, you probably know behind the scenes that there are no
> other sdhci-brcmstb-relevant controllers that "support cqe", but AFAICT
> I have no way of knowing that a priori. The driver and bindings give
> (too much?) flexibility.
> 
> Poking around, I think the only other one I might have missed would be
> gl9763e in sdhci-pci-gli.c. That also calls cqhci_init() but is
> otherwise relying on the default sdhci_pci_ops. So I'd either have to

It uses sdhci_gl9763e_ops not the default sdhci_pci_ops.  It looks OK
to me.

> change the common sdhci_pci_ops, or else start a new copy/paste/modify
> 'struct sdhci_ops' for it... This really does start to get messy when
> poking around on drivers I can't test. As in, it shouldn't be harmful
> to change most sdhci_reset() to sdhci_and_cqhci_reset() (as long as they
> aren't using some other CQE implementation), but the more invasive it
> gets (say, rewriting a bunch of other ops), the easier it is to get
> something wrong.

AFAICS it was just sdhci_am654_ops