linux-kernel - Re: [PATCH v2 03/10] scsi: ufs: Add LCC quirk for host and device

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Date:   Wed, 16 May 2018 14:11:17 -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,
        linux-arm-msm@...r.kernel.org,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-scsi-owner@...r.kernel.org
Subject: Re: [PATCH v2 03/10] scsi: ufs: Add LCC quirk for host and device

On 2018-05-03 04:07, Asutosh Das wrote:
> LCC (Line Control Command) is being used for communication between
> UFS host and UFS device. But some hosts might have the issue with
> issuing the LCC commands to UFS device and in this case LCC could be
> explicitly disabled.
> 
> But there could be a need where we don't want to disable the LCC
> on both host & device; hence this change splits the quirk in 2 parts
> one for host and one for device.
> 
> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
> Signed-off-by: Venkat Gopalakrishnan <venkatg@...eaurora.org>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 16 ++++++++++++++++
>  drivers/scsi/ufs/ufshcd.h | 12 ++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index f3083fe..6dabce8 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -4116,6 +4116,11 @@ static int ufshcd_disable_tx_lcc(struct ufs_hba
> *hba, bool peer)
>  	return err;
>  }
> 
> +static inline int ufshcd_disable_host_tx_lcc(struct ufs_hba *hba)
> +{
> +	return ufshcd_disable_tx_lcc(hba, false);
> +}
> +
>  static inline int ufshcd_disable_device_tx_lcc(struct ufs_hba *hba)
>  {
>  	return ufshcd_disable_tx_lcc(hba, true);
> @@ -4172,6 +4177,17 @@ static int ufshcd_link_startup(struct ufs_hba 
> *hba)
>  		ufshcd_dme_set(hba, UIC_ARG_MIB(TX_LCC_ENABLE), 1);
>  	}
> 
> +	if (hba->quirks & UFSHCD_BROKEN_LCC_PROCESSING_ON_HOST) {
> +		ret = ufshcd_disable_device_tx_lcc(hba);
> +		if (ret)
> +			goto out;
> +	}
> +
> +	if (hba->quirks & UFSHCD_BROKEN_LCC_PROCESSING_ON_DEVICE) {
> +		ret = ufshcd_disable_host_tx_lcc(hba);
> +		if (ret)
> +			goto out;
> +	}
>  	if (link_startup_again) {
>  		link_startup_again = false;
>  		retries = DME_LINKSTARTUP_RETRIES;
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index bb4ecfb..0417c42 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -598,6 +598,18 @@ struct ufs_hba {
>  	 * TX_LCC.
>  	 */
>  	#define UFSHCD_QUIRK_BROKEN_PWR_MODE_CHANGE		UFS_BIT(8)
> +
> +	/*
> +	 * If UFS device is having issue in processing LCC (Line Control
> +	 * Command) coming from UFS host controller then enable this quirk.
> +	 * When this quirk is enabled, host controller driver should disable
> +	 * the LCC transmission on UFS host controller (by clearing
> +	 * TX_LCC_ENABLE attribute of host to 0).
> +	 */
> +	#define UFSHCD_BROKEN_LCC_PROCESSING_ON_DEVICE		0x100
> +
> +	#define UFSHCD_BROKEN_LCC_PROCESSING_ON_HOST		0x200
> +
>  	unsigned int quirks;	/* Deviations from standard UFSHCI spec. */
> 
>  	/* Device deviations from standard UFS device spec. */

Please check if these quirks are really needed for commercial version of 
UFS host controllers.

-- 
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