linux-kernel - Re: [PATCH v2 09/11] scsi: ufs: exynos: set ACG to be controlled by UFS_ACG

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Message-ID: <f9cb758d-28a5-44bd-9cb5-d7ac5108db1b@linaro.org>
Date: Wed, 30 Oct 2024 11:45:15 +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 09/11] scsi: ufs: exynos: set ACG to be controlled by
 UFS_ACG_DISABLE



On 10/25/24 2:14 PM, Peter Griffin wrote:
> HCI_IOP_ACG_DISABLE is an undocumented register in the TRM but the
> downstream driver sets this register so we follow suit here.
> 
> The register is already 0 presumed to be set by the bootloader as
> the comment downstream implies the reset state is 1. So whilst this
> is a nop currently, it should help with suspend/resume.

It should help in case the bootloader changes I assume. I see
gs101_ufs_drv_init() gets called only at probe time, via
ufshcd_pltfrm_init().

> 
> Signed-off-by: Peter Griffin <peter.griffin@...aro.org>

Reviewed-by: Tudor Ambarus <tudor.ambarus@...aro.org>

> ---
>  drivers/ufs/host/ufs-exynos.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/ufs/host/ufs-exynos.c b/drivers/ufs/host/ufs-exynos.c
> index b0cbb147c7a1..fa4e61f152c4 100644
> --- a/drivers/ufs/host/ufs-exynos.c
> +++ b/drivers/ufs/host/ufs-exynos.c
> @@ -76,6 +76,10 @@
>  #define CLK_CTRL_EN_MASK	(REFCLK_CTRL_EN |\
>  				 UNIPRO_PCLK_CTRL_EN |\
>  				 UNIPRO_MCLK_CTRL_EN)
> +
> +#define HCI_IOP_ACG_DISABLE	0x100
> +#define HCI_IOP_ACG_DISABLE_EN	BIT(0)
> +
>  /* Device fatal error */
>  #define DFES_ERR_EN		BIT(31)
>  #define DFES_DEF_L2_ERRS	(UIC_DATA_LINK_LAYER_ERROR_RX_BUF_OF |\
> @@ -220,10 +224,15 @@ static int exynos_ufs_shareability(struct exynos_ufs *ufs)
>  static int gs101_ufs_drv_init(struct device *dev, struct exynos_ufs *ufs)
>  {
>  	struct ufs_hba *hba = ufs->hba;
> +	u32 reg;
>  
>  	/* Enable WriteBooster */
>  	hba->caps |= UFSHCD_CAP_WB_EN;
>  
> +	/* set ACG to be controlled by UFS_ACG_DISABLE */
> +	reg = hci_readl(ufs, HCI_IOP_ACG_DISABLE);
> +	hci_writel(ufs, reg & (~HCI_IOP_ACG_DISABLE_EN), HCI_IOP_ACG_DISABLE);
> +
>  	return exynos_ufs_shareability(ufs);
>  }
>