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

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Date:   Mon, 08 Nov 2021 23:48:42 +0900
From:   Tsuchiya Yuto <kitakar@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.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 Tue, 2021-11-02 at 14:26 +0300, Dan Carpenter wrote:
> 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 */
> >  	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 */
>         ^^^^^^^^^^^^^^^^^^^
> These two white space changes are unrelated.  Please do them in a
> separate patch.

Thank you for the review :-)

I thought these space fixes were too trivial for a separate patch, so
I made the fix while at it. I have no strong reason not to separate the
space fix. I'll do so in v2.

Regards,
Tsuchiya Yuto