linux-kernel - Re: [PATCH 02/17] media: atomisp: pci: fix punit_ddr_dvfs_enable() argument for mrfld

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Date:   Mon, 18 Oct 2021 14:07:59 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Tsuchiya Yuto <kitakar@...il.com>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Patrik Gfeller <patrik.gfeller@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Aline Santana Cordeiro <alinesantanacordeiro@...il.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Dinghao Liu <dinghao.liu@....edu.cn>,
        Alan <alan@...ux.intel.com>, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/17] media: atomisp: pci: fix punit_ddr_dvfs_enable()
 argument for mrfld_power up case

On Mon, Oct 18, 2021 at 01:19:42AM +0900, Tsuchiya Yuto wrote:
> When comparing with intel-aero atomisp [1], it looks like
> punit_ddr_dvfs_enable() should take `false` as an argument on mrfld_power
> up case.
> 
> Code from the intel-aero kernel [1]:
> 
>         int atomisp_mrfld_power_down(struct atomisp_device *isp)
>         {
>         [...]
>         	/*WA:Enable DVFS*/
>         	if (IS_CHT)
>         		punit_ddr_dvfs_enable(true);
> 
>         int atomisp_mrfld_power_up(struct atomisp_device *isp)
>         {
>         [...]
>         	/*WA for PUNIT, if DVFS enabled, ISP timeout observed*/
>         	if (IS_CHT)
>         		punit_ddr_dvfs_enable(false);
> 
> This patch fixes the inverted argument as per the intel-aero code, as
> well as its comment. While here, fix space issues for comments in
> atomisp_mrfld_power().
> 
> Note that it does not seem to be possible to unify the up/down cases for
> punit_ddr_dvfs_enable(), i.e., we can't do something like the following:
> 
>         if (IS_CHT)
>         	punit_ddr_dvfs_enable(!enable);
> 
> because according to the intel-aero code [1], the DVFS is disabled
> before "writing 0x0 to ISPSSPM0 bit[1:0]" and the DVFS is enabled after
> "writing 0x3 to ISPSSPM0 bit[1:0]".
> 
> [1] https://github.com/intel-aero/linux-kernel/blob/a1b673258feb915268377275130c5c5df0eafc82/drivers/media/pci/atomisp/atomisp_driver/atomisp_v4l2.c#L431-L514
> 
> Fixes: 0f441fd70b1e ("media: atomisp: simplify the power down/up code")
> Signed-off-by: Tsuchiya Yuto <kitakar@...il.com>
> ---
>  drivers/staging/media/atomisp/pci/atomisp_v4l2.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_v4l2.c b/drivers/staging/media/atomisp/pci/atomisp_v4l2.c
> index 0511c454e769..f5362554638e 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_v4l2.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_v4l2.c
> @@ -711,15 +711,15 @@ static int atomisp_mrfld_power(struct atomisp_device *isp, bool enable)
>  
>  	dev_dbg(isp->dev, "IUNIT power-%s.\n", enable ? "on" : "off");
>  
> -	/*WA:Enable DVFS*/
> +	/* WA for PUNIT, if DVFS enabled, ISP timeout observed */

P-Unit

>  	if (IS_CHT && enable)
> -		punit_ddr_dvfs_enable(true);
> +		punit_ddr_dvfs_enable(false);
>  
>  	/*
>  	 * FIXME:WA for ECS28A, with this sleep, CTS
>  	 * android.hardware.camera2.cts.CameraDeviceTest#testCameraDeviceAbort
>  	 * PASS, no impact on other platforms
> -	*/
> +	 */
>  	if (IS_BYT && enable)
>  		msleep(10);
>  
> @@ -727,7 +727,7 @@ static int atomisp_mrfld_power(struct atomisp_device *isp, bool enable)
>  	iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, MRFLD_ISPSSPM0,
>  			val, MRFLD_ISPSSPM0_ISPSSC_MASK);
>  
> -	/*WA:Enable DVFS*/
> +	/* WA:Enable DVFS */
>  	if (IS_CHT && !enable)
>  		punit_ddr_dvfs_enable(true);
>  
> -- 
> 2.33.1
> 
> 

-- 
With Best Regards,
Andy Shevchenko