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

[Bart Van Assche]

On 8/14/24 10:16 PM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>
> 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.

Since this patch by itself looks good to me:

Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>