linux-kernel - Re: [PATCH v2 21/66] media: sun6i-csi: Always set exclusive module clock rate

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Date:   Tue, 1 Mar 2022 16:39:51 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-clk@...r.kernel.org, linux-staging@...ts.linux.dev,
        Yong Deng <yong.deng@...ewell.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Helen Koike <helen.koike@...labora.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 21/66] media: sun6i-csi: Always set exclusive module
 clock rate

Hi Sakari,

On Mon 14 Feb 22, 18:31, Sakari Ailus wrote:
> Hi Paul,
> 
> Thanks for the patchbomb.

I'll split it in the next revision.
 
> On Sat, Feb 05, 2022 at 07:53:44PM +0100, Paul Kocialkowski wrote:
> > In some situations the default rate of the module clock is not the
> > required one for operation (for example when reconfiguring the clock
> > tree to use a different parent). As a result, always set the correct
> > rate for the clock (and take care of cleanup).
> > 
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> > ---
> >  .../platform/sunxi/sun6i-csi/sun6i_csi.c      | 54 ++++++++++++++-----
> >  1 file changed, 41 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 8155e9560164..2355088fdc37 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -856,28 +849,53 @@ static int sun6i_csi_resources_setup(struct sun6i_csi_device *csi_dev,
> >  		return PTR_ERR(csi_dev->clk_ram);
> >  	}
> >  
> > +	if (of_device_is_compatible(dev->of_node, "allwinner,sun50i-a64-csi"))
> > +		clk_mod_rate = 300000000;
> > +	else
> > +		clk_mod_rate = 297000000;
> 
> This would be nice to put in OF match data.
> 
> Of course the driver did this already before the patch. The approach still
> scales badly.

Agreed, that could be another follow-up patch in the sun6i-csi rework series.

Paul

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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