Re: [PATCH V1 2/2] scsi: ufs: ufs-qcom: Enable SKIP DEVICE RESET Quirk

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

On 5/31/26 4:50 PM, Nitin Rawat wrote:
> -
> -	/* reset the connected UFS device during power down */
> -	if (ufs_qcom_is_link_off(hba) && host->device_reset) {
> +	/*
> +	 * For some UFS vendors, skip asserting device reset here.
> +	 * These vendor parts keep drawing larger current after reset
> +	 * is asserted until it is deasserted, and the 10ms delay is
> +	 * not sufficient to prevent OCP (Over Current Protection)
> +	 * on the regulator. This is for the powerdown case, so
> +	 * the device reset can be asserted later as part of the
> +	 * platform shutdown sequence.
> +	 */
> +	if (ufs_qcom_is_link_off(hba) && host->device_reset &&
> +	    !(hba->quirks & UFSHCD_QUIRK_SKIP_DEVICE_RESET)) {
>   		ufs_qcom_device_reset_ctrl(hba, true);
>   		/*
>   		 * After sending the SSU command, asserting the rst_n
> @@ -1288,6 +1296,19 @@ static struct ufs_dev_quirk ufs_qcom_dev_fixups[] = {
>   static void ufs_qcom_fixup_dev_quirks(struct ufs_hba *hba)
>   {
>   	ufshcd_fixup_dev_quirks(hba, ufs_qcom_dev_fixups);
> +
> +	/*
> +	 * Some UFS parts keep drawing larger current after reset is asserted
> +	 * until it is deasserted. The 10ms delay added after asserting HWRST
> +	 * (as done for other vendors) is not sufficient for these parts.
> +	 *
> +	 * Skip asserting device reset during UFS power down for these parts
> +	 * to prevent OCP (Over Current Protection) fault on the regulator.
> +	 * This is handled only in shutdown; the device reset will be asserted
> +	 * as part of the platform shutdown sequence.
> +	 */
> +	if (hba->dev_info.wmanufacturerid == UFS_VENDOR_MICRON)
> +		hba->quirks |= UFSHCD_QUIRK_SKIP_DEVICE_RESET;
>   }

Why has this fix been implemented in the ufs-qcom.c source file? Isn't
this an issue that affects all host controllers?

Thanks,

Bart.