linux-kernel - Re: [PATCH 2/3] ufs: core: Add a quirk for handling broken SDBS field in controller capabilities register

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Message-ID: <f51533d5-46b9-4485-b71c-2fbd6a12071a@acm.org>
Date: Wed, 14 Aug 2024 10:29:11 -0700
From: Bart Van Assche <bvanassche@....org>
To: manivannan.sadhasivam@...aro.org, Alim Akhtar <alim.akhtar@...sung.com>,
 Avri Altman <avri.altman@....com>,
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
 "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, Kyoungrul Kim <k831.kim@...sung.com>
Subject: Re: [PATCH 2/3] ufs: core: Add a quirk for handling broken SDBS field
 in controller capabilities register

On 8/14/24 10:15 AM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> 'Legacy Queue & Single Doorbell Support (SDBS)' field in the controller
> capabilities register is supposed to be reserved for UFSHCI 3.0 based
> controllers and should read as 0. But some controllers may report bogus
> value of 1 due to the hardware bug. So let's add a quirk to handle those
> controllers.
> 
> If the quirk is enabled by the controller driver and MCQ is not supported,
> then 'hba->sdbs_sup' field will be ignored and the SCSI device will be
> added in legacy/single doorbell mode.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>   drivers/ufs/core/ufshcd.c | 5 +++--
>   include/ufs/ufshcd.h      | 7 +++++++
>   2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 168b9dbc3ada..acb6f261ecc2 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -10512,8 +10512,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
>   	}
>   
>   	if (!is_mcq_supported(hba)) {
> -		if (!hba->sdbs_sup) {
> -			dev_err(hba->dev, "%s: failed to initialize (legacy doorbell mode not supported)\n",
> +		if (!(hba->quirks & UFSHCD_QUIRK_BROKEN_SDBS_CAP) && !hba->sdbs_sup) {
> +			dev_err(hba->dev,
> +				"%s: failed to initialize (legacy doorbell mode not supported)\n",
>   				__func__);
>   			err = -EINVAL;
>   			goto out_disable;

Adding a check for the UFSHCD_QUIRK_BROKEN_SDBS_CAP quirk everywhere
hba->sdbs_sup is tested is wrong. Please move this check to the code
that assigns a value to hba->sdbs_sup.

Thanks,

Bart.