RE: [PATCH v2 5/5] arm64: dts: renesas: r9a07g043u11-smarc-cru-csi-ov5645: Reduce I2C frequency

From: Biju Das <biju.das.jz@bp.renesas.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Jacopo Mondi <jacopo.mondi@ideasonboard.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Magnus Damm <magnus.damm@gmail.com>,
	"linux-renesas-soc@vger.kernel.org"
	<linux-renesas-soc@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	biju.das.au <biju.das.au@gmail.com>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: RE: [PATCH v2 5/5] arm64: dts: renesas: r9a07g043u11-smarc-cru-csi-ov5645: Reduce I2C frequency
Date: Sun, 11 Feb 2024 16:13:46 +0000	[thread overview]
Message-ID: <TYCPR01MB11269102490F2707ADEEA9FF686492@TYCPR01MB11269.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <ZcZCGZn0xHMHVVD1@kekkonen.localdomain>

Hi Sakari Ailus,

> -----Original Message-----
> From: Sakari Ailus <sakari.ailus@linux.intel.com>
> Sent: Friday, February 9, 2024 3:18 PM
> Subject: Re: [PATCH v2 5/5] arm64: dts: renesas: r9a07g043u11-smarc-cru-
> csi-ov5645: Reduce I2C frequency
> 
> Hi folks,
> 
> On Fri, Feb 09, 2024 at 02:36:22PM +0000, Biju Das wrote:
> > Hi Geert,
> >
> > > -----Original Message-----
> > > From: Biju Das
> > > Sent: Tuesday, January 30, 2024 2:15 PM
> > > Subject: RE: [PATCH v2 5/5] arm64: dts: renesas:
> > > r9a07g043u11-smarc-cru-
> > > csi-ov5645: Reduce I2C frequency
> > >
> > > Hi Geert,
> > >
> > > > -----Original Message-----
> > > > From: Biju Das
> > > > Sent: Friday, January 26, 2024 3:57 PM
> > > > Subject: RE: [PATCH v2 5/5] arm64: dts: renesas:
> > > > r9a07g043u11-smarc-cru-
> > > > csi-ov5645: Reduce I2C frequency
> > > >
> > > > Hi Geert,
> > > >
> > > > Thanks for the feedback.
> > > >
> > > > > -----Original Message-----
> > > > > From: Geert Uytterhoeven <geert@linux-m68k.org>
> > > > > Sent: Friday, January 26, 2024 1:53 PM
> > > > > Subject: Re: [PATCH v2 5/5] arm64: dts: renesas:
> > > > > r9a07g043u11-smarc-cru-
> > > > > csi-ov5645: Reduce I2C frequency
> > > > >
> > > > > Hi Biju,
> > > > >
> > > > > On Fri, Jan 26, 2024 at 2:31 PM Biju Das
> > > > > <biju.das.jz@bp.renesas.com>
> > > > > wrote:
> > > > > > Reduce i2c freq from 400->100 kHz on RZ/G2UL SMARC EVK as the
> > > > > > captured image is not proper with the sensor configuration over
> I2C.
> > > > > >
> > > > > > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > > > >
> > > > > Thanks for your patch!
> > > > >
> > > > > > ---
> > > > > > a/arch/arm64/boot/dts/renesas/r9a07g043u11-smarc-cru-csi-ov564
> > > > > > 5.dt
> > > > > > so
> > > > > > +++ b/arch/arm64/boot/dts/renesas/r9a07g043u11-smarc-cru-csi-
> ov5645.
> > > > > > +++ dt
> > > > > > +++ so
> > > > > > @@ -19,3 +19,7 @@ &ov5645 {
> > > > > >         enable-gpios = <&pinctrl RZG2L_GPIO(4, 4)
> GPIO_ACTIVE_HIGH>;
> > > > > >         reset-gpios = <&pinctrl RZG2L_GPIO(0, 1)
> > > > > > GPIO_ACTIVE_LOW>; };
> > > > > > +
> > > > > > +&i2c0 {
> > > > > > +       clock-frequency = <100000>; };
> > > > >
> > > > > Is this a limitation of one of the I2C devices on the bus, or a
> > > > > PCB design issue?
> > > >
> > > > Currently versa3 clock generator connected to the same bus and it
> > > > works ok with 400kHz clock. Maybe it is stressed not that much
> > > > compared to OV5645 sensor configuration.
> > > >
> > > > At the moment with 400kHz I2C bus clock, Camera capture is not
> > > > working properly on RZ/G2UL, but with same bus frequency the same
> > > > works fine on RZ/{G2L,G2LC,V2L}.
> > > > There may be some hardware differences which is causing this issue.
> > > >
> > > > >
> > > > > Doesn't this need a Fixes tag?
> > > >
> > > > I can create a new patch updating bus frequency as 100kHz and add
> > > > fixes tag.
> > > > After this I will drop this patch as it no longer needed.
> > > >
> > > > Please let me know.
> > >
> > > + media
> > >
> > > Adding a delay after Software reset makes it to work at 400kHz with
> > > RZ/G2UL SMARC EVK.
> > >
> > > So not sure we need to add delay after software reset?
> > >
> > > Now after OV5645 gpio reset, then there is 20msec delay and then
> > > again we are issuing software reset and there is no delay after this
> > > for this software reset.
> > >
> > > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > > index a26ac11c989d..d67a5e23fe5a 100644
> > > --- a/drivers/media/i2c/ov5645.c
> > > +++ b/drivers/media/i2c/ov5645.c
> > > @@ -622,11 +622,19 @@ static int ov5645_set_register_array(struct
> > > ov5645 *ov5645,  {
> > >         unsigned int i;
> > >         int ret;
> > >
> > >         for (i = 0; i < num_settings; ++i, ++settings) {
> > >                 ret = ov5645_write_reg(ov5645, settings->reg,
> > > settings-
> > > >val);
> > >                 if (ret < 0)
> > >                         return ret;
> > > +
> > > +               if (settings->reg == OV5645_SYSTEM_CTRL0)
> > > +                       fsleep(1000);
> > >
> >
> > This issue seen on RZ/G2L SMARC EVK as well. My testing on G2L family
> > shows we need to add delay to make OV5645 to work @400kHZ.
> 
> Typically there's a delay before the chip is accessible over I²C after
> resetting it. It's a bit open whether this one needs it, very probably it
> does. It'd be nicer nonetheless to do this outside the register list and
> instead use a separate ov5645_write_reg() call.

OK.
> 
> Probably the first write is redundant. The second write resets the device.
> 0x80 should be sufficient value for that.

Will test and send patch for it.

Cheers,
Biju