Re: [PATCH v2] ufs: bsg: Add hibern8 enter/exit to ufshcd_send_bsg_uic_cmd

[Bart Van Assche <bvanassche@acm.org>]

On 4/14/25 5:02 AM, Arthur Simchaev wrote:
> This patch adds functionality to allow user-level applications to send
> the Hibern8 Enter command via the BSG framework. With this feature,
> applications can perform H8 stress tests. Also can be used as one
> of the triggers for the Eye monitor measurement feature added to the
> M-PHY v5 specification.
> For completion, allow the sibling functionality of hibern8 exit as well.
> 
> Signed-off-by: Arthur Simchaev <arthur.simchaev@sandisk.com>
> 
> ---
> Changed since v1:
>   - elaborate commit log
> ---
>   drivers/ufs/core/ufshcd.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index be65fc4b5ccd..536b54ccc860 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -4363,6 +4363,16 @@ int ufshcd_send_bsg_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
>   		goto out;
>   	}
>   
> +	if (uic_cmd->command == UIC_CMD_DME_HIBER_ENTER) {
> +		ret = ufshcd_uic_hibern8_enter(hba);
> +		goto out;
> +	}
> +
> +	if (uic_cmd->command == UIC_CMD_DME_HIBER_EXIT) {
> +		ret = ufshcd_uic_hibern8_exit(hba, uic_cmd);
> +		goto out;
> +	}
> +
>   	mutex_lock(&hba->uic_cmd_mutex);
>   	ufshcd_add_delay_before_dme_cmd(hba);

This is wrong. The BSG interface shouldn't alter the power state without
informing the SCSI core about these power state changes. Please use
existing sysfs attributes to modify the power state or add new sysfs
attributes if necessary.

Bart.