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: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: 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: Tue, 30 Jan 2024 14:15:01 +0000	[thread overview]
Message-ID: <TYCPR01MB11269379C39A0242C9F87A40E867D2@TYCPR01MB11269.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <TYCPR01MB11269FEE3A8C6D695CBBACEE086792@TYCPR01MB11269.jpnprd01.prod.outlook.com>

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-ov5645.dtso
> > > +++ 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);

Cheers,
Biju
