Re: [PATCH v2 3/3] ufs: qcom: Add UFSHCD_QUIRK_BROKEN_LSDBS_CAP for SM8550 SoC

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Thu, Aug 15, 2024 at 11:01:47AM -0700, Bart Van Assche wrote:
> On 8/14/24 10:16 PM, Manivannan Sadhasivam via B4 Relay wrote:
> > From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > 
> > SM8550 SoC supports the UFSHCI 3.0 spec, but it reports a bogus value of
> > 1 in the reserved 'Legacy Queue & Single Doorbell Support (LSDBS)' field of
> > the Controller Capabilities register. This field is supposed to read 0 as
> > per the spec.
> > 
> > But starting with commit 0c60eb0cc320 ("scsi: ufs: core: Check LSDBS cap
> > when !mcq"), ufshcd driver is now relying on the LSDBS field to decide when
> > to use the legacy doorbell mode if MCQ is not supported. And this ends up
> > breaking UFS on SM8550:
> > 
> > ufshcd-qcom 1d84000.ufs: ufshcd_init: failed to initialize (legacy doorbell mode not supported)
> > ufshcd-qcom 1d84000.ufs: error -EINVAL: Initialization failed with error -22
> > 
> > So use the UFSHCD_QUIRK_BROKEN_LSDBS_CAP quirk for SM8550 SoC so that the
> > ufshcd driver could use legacy doorbell mode correctly.
> > 
> > Fixes: 0c60eb0cc320 ("scsi: ufs: core: Check LSDBS cap when !mcq")
> 
> Since this patch depends on the previous two patches, the previous two
> patches probably need a "Cc: stable" tag. Otherwise the stable
> maintainers will have a hard time figuring out which patches this patch
> depends on.
> 

Well, I have not CCed stable list for this patch intentionally as the offending
commit got merged in v6.11-rc2. So there is no need of backport. Once this
series gets merged into one of the v6.11-rcS, all will be good.

> Since this patch by itself looks good to me:
> 
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> 

Thanks!

- Mani

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