linux-kernel - Re: [PATCH v2 01/10] scsi: ufs: Allowing power mode change

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Message-ID: <33a5e196be45bfeb0bea49a446e8af98@codeaurora.org>
Date:   Wed, 16 May 2018 14:09:51 -0700
From:   Subhash Jadavani <subhashj@...eaurora.org>
To:     Asutosh Das <asutoshd@...eaurora.org>
Cc:     cang@...eaurora.org, vivek.gautam@...eaurora.org,
        rnayak@...eaurora.org, vinholikatti@...il.com,
        jejb@...ux.vnet.ibm.com, martin.petersen@...cle.com,
        linux-mmc@...r.kernel.org, linux-scsi@...r.kernel.org,
        Yaniv Gardi <ygardi@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/10] scsi: ufs: Allowing power mode change

On 2018-05-03 04:07, Asutosh Das wrote:
> From: Yaniv Gardi <ygardi@...eaurora.org>
> 
> Due to M-PHY issues, moving from HS to any other mode or gear or
> even Hibern8 may cause some un-predicted behavior
> of the device.
> This patch adds provides a quirk to address that.
> 
> Signed-off-by: Yaniv Gardi <ygardi@...eaurora.org>
> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 8 +++++++-
>  drivers/scsi/ufs/ufshcd.h | 7 +++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 5bc9dc1..f3083fe 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -4162,9 +4162,15 @@ static int ufshcd_link_startup(struct ufs_hba 
> *hba)
>  			goto out;
>  	} while (ret && retries--);
> 
> -	if (ret)
> +	if (ret) {
>  		/* failed to get the link up... retire */
>  		goto out;
> +	}
> +
> +	if (hba->quirks & UFSHCD_QUIRK_BROKEN_PWR_MODE_CHANGE) {
> +		ufshcd_dme_set(hba, UIC_ARG_MIB(TX_LCC_ENABLE), 0);
> +		ufshcd_dme_set(hba, UIC_ARG_MIB(TX_LCC_ENABLE), 1);
> +	}
> 
>  	if (link_startup_again) {
>  		link_startup_again = false;
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index cbe46f6..bb4ecfb 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -591,6 +591,13 @@ struct ufs_hba {
>  	 */
>  	#define UFSHCD_QUIRK_PRDT_BYTE_GRAN			UFS_BIT(7)
> 
> +	/*
> +	 * Needs to be enabled if moving from HS to any other gear/mode or 
> even
> +	 * hibern8 causes unpredicted behavior of device.
> +	 * If this quirk is enabled, standard UFS driver will disable/enable
> +	 * TX_LCC.
> +	 */
> +	#define UFSHCD_QUIRK_BROKEN_PWR_MODE_CHANGE		UFS_BIT(8)
>  	unsigned int quirks;	/* Deviations from standard UFSHCI spec. */
> 
>  	/* Device deviations from standard UFS device spec. */

This was probably needed in early generation of UFS devices (non 
commercial) and may not be really needed now. I believe we can skip this 
patch.

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