linux-kernel - Re: [PATCH v2 11/11] scsi: ufs: exynos: gs101: enable clock gating with hibern8

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Message-ID: <6d3beeab-c26d-4240-b968-cb13d06d7eae@linaro.org>
Date: Wed, 30 Oct 2024 12:25:24 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Peter Griffin <peter.griffin@...aro.org>, alim.akhtar@...sung.com,
 James.Bottomley@...senPartnership.com, martin.petersen@...cle.com,
 avri.altman@....com, bvanassche@....org, krzk@...nel.org
Cc: andre.draszik@...aro.org, kernel-team@...roid.com,
 willmcvicker@...gle.com, linux-scsi@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
 ebiggers@...nel.org
Subject: Re: [PATCH v2 11/11] scsi: ufs: exynos: gs101: enable clock gating
 with hibern8



On 10/25/24 2:14 PM, Peter Griffin wrote:
> Enable clock gating and hibern8 capabilities for gs101. This
> leads to a significantly cooler phone when running the upstream
> kernel.
> 
> The exynos_ufs_post_hibern8() hook is also updated to remove the
> UIC_CMD_DME_HIBER_EXIT code path as this causes a hang on gs101.
> 
> The code path is removed rather than re-factored as no other SoC
> in ufs-exynos driver sets UFSHCD_CAP_HIBERN8_WITH_CLK_GATING
> capability. Additionally until the previous commit the hibern8
> callbacks were broken anyway as they expected a bool.

I think too it's fine to remove uneeded code as it was broken anyway.

> 
> Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
> ---
>  drivers/ufs/host/ufs-exynos.c | 24 ++++--------------------
>  1 file changed, 4 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-exynos.c b/drivers/ufs/host/ufs-exynos.c
> index 3bbb71f7bae7..7c8195f27bb6 100644
> --- a/drivers/ufs/host/ufs-exynos.c
> +++ b/drivers/ufs/host/ufs-exynos.c
cut

> @@ -1566,26 +1569,7 @@ static void exynos_ufs_post_hibern8(struct ufs_hba *hba, enum uic_cmd_dme cmd)
>  {

cut

> +	if (cmd == UIC_CMD_DME_HIBER_ENTER) {

I verified that the order of operations at hibern8_enter/exit() is sane:
Reviewed-by: Tudor Ambarus <tudor.ambarus@...aro.org>

---
hibern8_notify() gets called in ufshcd_uic_hibern8_enter/exit()

exynos_ufs_post_hibern8 disables the clocks for:
  ufshcd_vops_hibern8_notify(hba, UIC_CMD_DME_HIBER_ENTER, POST_CHANGE)

exynos_ufs_pre_hibern8() enables the clocks for:
  ufshcd_vops_hibern8_notify(hba, UIC_CMD_DME_HIBER_EXIT, PRE_CHANGE);