Re: [PATCH] scsi: ufs: core: Skip link param validation when lanes_per_direction is unset

[mani@xxxxxxxxxx]

On Wed, May 20, 2026 at 04:00:09PM +0900, Daejun Park wrote:
> ufshcd_validate_link_params(), added by commit e72323f3b09f ("scsi: ufs:
> core: Configure only active lanes during link"), is called
> unconditionally from ufshcd_link_startup() and fails link startup with
> -ENOLINK when the connected lane count read from the device differs from
> hba->lanes_per_direction.
> 
> lanes_per_direction is only set by ufshcd-pltfrm (default 2, or the
> "lanes-per-direction" devicetree property); ufshcd-pci controllers
> (e.g. Intel) leave it 0. As the device always reports >= 1 connected
> lanes, the check can never match and link startup always fails.
> Reproduced with QEMU's UFS device.
> 
> Skip the check when lanes_per_direction is unset: with no expected value
> to validate against, restore the behaviour from before that commit.
> 
> Fixes: e72323f3b09f ("scsi: ufs: core: Configure only active lanes during link")
> Signed-off-by: Daejun Park <daejun7.park@xxxxxxxxxxx>

Reviewed-by: Manivannan Sadhasivam <mani@xxxxxxxxxx>

- Mani

> ---
>  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 1aad1c03c3fc..0a510f43ce76 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -5222,6 +5222,16 @@ static int ufshcd_validate_link_params(struct ufs_hba *hba)
>  {
>  	int ret, val;
>  
> +	/*
> +	 * lanes_per_direction is only populated by the platform glue (it
> +	 * defaults to 2 or is read from the "lanes-per-direction" devicetree
> +	 * property). Controllers probed via ufshcd-pci leave it unset (0), in
> +	 * which case there is no expected lane count to validate the connected
> +	 * lanes against. Skip the check instead of failing link startup.
> +	 */
> +	if (!hba->lanes_per_direction)
> +		return 0;
> +
>  	ret = ufshcd_dme_get(hba, UIC_ARG_MIB(PA_CONNECTEDTXDATALANES),
>  			     &val);
>  	if (ret)
> 
> base-commit: 016d484531e3169cd7bcb26e0ac2c5523080809f
> -- 
> 2.43.0
> 

-- 
மணிவண்ணன் சதாசிவம்