Re: [PATCH V1 1/2] scsi: ufs: core: Add UFSHCD_QUIRK_SKIP_DEVICE_RESET quirk

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 6/1/26 1:50 AM, Nitin Rawat wrote:
> Add a new host quirk UFSHCD_QUIRK_SKIP_DEVICE_RESET to allow host
> controller drivers to skip asserting device reset during UFS power
> down.
> 
> When RST_N is asserted, the UFS device firmware wakes up and executes
> its internal reset routine. This routine initializes multiple hardware
> blocks and causing the device to draw a large curreny during this time.
> If the power rail transitions to LPM (Low Power Mode) while the device
> is still drawing this elevated current, it may trigger an
> OCP (Over Current Protection) fault in the regulator.
> 
> For some UFS devices (e.g., Micron), the elevated current draw persists
> until the reset line is deasserted, making a fixed delay insufficient
> to prevent OCP. This quirk allows such devices to skip device reset
> during UFS power down. The device reset will instead be asserted as
> part of the platform shutdown sequence.
> 
> Signed-off-by: Nitin Rawat <nitin.rawat@oss.qualcomm.com>
> ---
>  include/ufs/ufshcd.h | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index 3eaae082329c..18d634499ce5 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -813,6 +813,20 @@ enum ufshcd_quirks {
>  	 * allowed by M-PHY spec ver 6.0.
>  	 */
>  	UFSHCD_QUIRK_EXTENDED_TX_EQTR_ADAPT_LENGTH_L0L1L2L3	= 1 << 28,
> +
> +	/*
> +	 * Some UFS devices keep drawing larger current after reset is
> +	 * asserted until it is deasserted. Asserting device reset
> +	 * during UFS power down causes the device firmware to wake up and
> +	 * execute its reset routine, drawing current beyond the permissible
> +	 * limit for low-power mode (LPM). This may trigger an OCP fault on

Is that UFS-LPM, or Qualcomm-regulator-LPM?

Konrad


> +	 * the regulator supplying power to UFS.
> +	 *
> +	 * Enable this quirk to skip asserting device reset during UFS power
> +	 * down. This is handled only in shutdown; the device reset will be
> +	 * asserted as part of the platform shutdown sequence.
> +	 */
> +	UFSHCD_QUIRK_SKIP_DEVICE_RESET			= 1 << 29,
>  };
> 
>  enum ufshcd_caps {
> --
> 2.34.1
> 
>