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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 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 ? > [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