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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cp6FuxyMS+1ByUBjPxoD3NwLVLlSPXMt0GftNsobXo8=; b=Wrx3A756Kc2aTSZsiXstWXddgcdZsv9dj5sxS7pJmBHmOcyVQEkAKDRSE2YwvKjYuG o/3PmTFfw+oeMX0s/B32lZ8Xp+GQd8b+cw6J6LTj0m1hFtfh2IUV8rtaBiwpHdNuLcm5 S48C2G0jYOfolSPKA8mLsnAsbtZupC/UbZcPahuKOufC47y0ykGUeQVVj0KG09cWAXYL hAz5ftDV7Y8GcvR2Gi//1+TAvmLquzRFU9egQBC1B0uHHKeDYE2gi7nvy2+ncNuCPT81 5HzxKap3ECuINhhDtEapHh6oIZ2VdLKJc4t4Mst7g+8+yteg77XjkeZNlJ8gUdu7m3Id TmiA== X-Gm-Message-State: ANhLgQ0JuIlNba8KX7Xu3GgeEs+IT8yrxhpLk8zinAL62i/N7COvOw/7 /sZcmoi1XJl5JcuyLkLbJ8dtBWxYwu96QW7wNqs= X-Google-Smtp-Source: ADFU+vvUwftzmRRclxvvzyhLsc/9O0HFBYAoNjwm2ZtXWTEFy5i/ZJJVw6mYIkj76FgQsO8L29zPqCTxgnWSadb1+Og= X-Received: by 2002:a9d:64cd:: with SMTP id n13mr1286943otl.274.1584604849293; Thu, 19 Mar 2020 01:00:49 -0700 (PDT) MIME-Version: 1.0 References: <1584133954-6953-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <1584133954-6953-4-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <20200313212345.GM4751@pendragon.ideasonboard.com> <20200318232236.GJ24538@pendragon.ideasonboard.com> In-Reply-To: <20200318232236.GJ24538@pendragon.ideasonboard.com> From: "Lad, Prabhakar" Date: Thu, 19 Mar 2020 08:00:22 +0000 Message-ID: Subject: Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000 To: Laurent Pinchart X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200319_010051_540054_B72D5CD7 X-CRM114-Status: GOOD ( 25.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , "devicetree@vger.kernel.org" , Pengutronix Kernel Team , Ezequiel Garcia , Sascha Hauer , Magnus Damm , Prabhakar Mahadev Lad , "linux-kernel@vger.kernel.org" , "linux-renesas-soc@vger.kernel.org" , Rob Herring , Geert Uytterhoeven , NXP Linux Team , Sakari Ailus , Shawn Guo , Mauro Carvalho Chehab , Fabio Estevam , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Laurent, On Wed, Mar 18, 2020 at 11:22 PM Laurent Pinchart wrote: > > Hi Prabhakar, > > On Wed, Mar 18, 2020 at 10:41:57PM +0000, Lad, Prabhakar wrote: > > On Fri, Mar 13, 2020 at 9:31 PM Prabhakar Mahadev Lad wrote: > > > On 13 March 2020 21:24, Laurent Pinchart wrote: > > >> On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote: > > >>> While testing on Renesas RZ/G2E platform, noticed the clock frequency > > >>> to be 24242424 as a result the probe failed. However increasing the > > >>> maximum leverage of external clock frequency to 24480000 fixes this > > >>> issue. Since this difference is small enough and is insignificant set > > >>> the same in the driver. > > >>> > > >>> Signed-off-by: Lad Prabhakar > > >>> --- > > >>> drivers/media/i2c/ov5645.c | 6 ++++-- > > >>> 1 file changed, 4 insertions(+), 2 deletions(-) > > >>> > > >>> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c > > >>> index 4fbabf3..b49359b 100644 > > >>> --- a/drivers/media/i2c/ov5645.c > > >>> +++ b/drivers/media/i2c/ov5645.c > > >>> @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client) > > >>> } > > >>> > > >>> xclk_freq = clk_get_rate(ov5645->xclk); > > >>> -/* external clock must be 24MHz, allow 1% tolerance */ > > >>> -if (xclk_freq < 23760000 || xclk_freq > 24240000) { > > >>> +/* external clock must be 24MHz, allow a minimum 1% and a > > >> maximum of 2% > > >>> + * tolerance > > >> > > >> So where do these numbers come from ? I understand that 2% is what you > > >> need to make your clock fit in the range, but why -1%/+2% instead of - > > >> 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the > > >> range of supported xvclk frequencies to be 6MHz to 54MHz. I understand > > >> that PLL parameters depend on the clock frequency, but could they be > > >> calculated instead of hardcoded, to avoid requiring an exact 24MHz input > > >> frequency ? > > >> > > > To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the > > > logs/comment says 24Mhz. > > > > > Comparing to ov5640 datasheet [1] (which I am assuming might be > > similar to ov5645), > > Let's assume this to be the case, I see no reason not to :-) > > > this change should affect the driver. > > How do you mean ? > Oops sorry for for the typo I meant shouldn't affect the driver :) Cheers, --Prabhakar > > [1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf > > > > >>> + */ > > >>> +if (xclk_freq < 23760000 || xclk_freq > 24480000) { > > >>> dev_err(dev, "external clock frequency %u is not supported\n", > > >>> xclk_freq); > > >>> return -EINVAL; > > -- > Regards, > > Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel