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charset=us-ascii Content-Disposition: inline In-Reply-To: <20250224161640.GA6778@pendragon.ideasonboard.com> Hi Laurent, On Mon, Feb 24, 2025 at 06:16:40PM +0200, Laurent Pinchart wrote: > On Mon, Feb 24, 2025 at 02:38:35PM +0000, Sakari Ailus wrote: > > On Mon, Feb 24, 2025 at 03:25:36PM +0200, Laurent Pinchart wrote: > > > On Mon, Feb 24, 2025 at 12:49:48PM +0000, Sakari Ailus wrote: > > > > On Mon, Feb 24, 2025 at 02:24:29PM +0200, Tomi Valkeinen wrote: > > > > > On 24/02/2025 13:54, Mehdi Djait wrote: > > > > > > On Mon, Feb 24, 2025 at 09:42:12AM +0000, Sakari Ailus wrote: > > > > > > > On Mon, Feb 24, 2025 at 08:59:34AM +0100, Mehdi Djait wrote: > > > > > > > > On Mon, Feb 24, 2025 at 01:06:49AM +0200, Laurent Pinchart wrote: > > > > > > > > > On Thu, Feb 20, 2025 at 04:49:09PM +0100, Mehdi Djait wrote: > > > > > > > > > > Make the clock producer reference lookup optional > > > > > > > > > > > > > > > > > > > > Add support for ACPI-based platforms by parsing the 'clock-frequency' > > > > > > > > > > property when no clock producer is available > > > > > > > > > > > > > > > > > > > > Signed-off-by: Mehdi Djait > > > > > > > > > > --- > > > > > > > > > > drivers/media/i2c/imx219.c | 14 ++++++++++++-- > > > > > > > > > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c > > > > > > > > > > index 2d54cea113e1..a876a6d80a47 100644 > > > > > > > > > > --- a/drivers/media/i2c/imx219.c > > > > > > > > > > +++ b/drivers/media/i2c/imx219.c > > > > > > > > > > @@ -1103,12 +1103,22 @@ static int imx219_probe(struct i2c_client *client) > > > > > > > > > > "failed to initialize CCI\n"); > > > > > > > > > > /* Get system clock (xclk) */ > > > > > > > > > > - imx219->xclk = devm_clk_get(dev, NULL); > > > > > > > > > > + imx219->xclk = devm_clk_get_optional(dev, NULL); > > > > > > > > > > if (IS_ERR(imx219->xclk)) > > > > > > > > > > return dev_err_probe(dev, PTR_ERR(imx219->xclk), > > > > > > > > > > "failed to get xclk\n"); > > > > > > > > > > - imx219->xclk_freq = clk_get_rate(imx219->xclk); > > > > > > > > > > + if (imx219->xclk) { > > > > > > > > > > + imx219->xclk_freq = clk_get_rate(imx219->xclk); > > > > > > > > > > + } else { > > > > > > > > > > + ret = fwnode_property_read_u32(dev_fwnode(dev), > > > > > > > > > > + "clock-frequency", > > > > > > > > > > + &imx219->xclk_freq); > > > > > > > > > > + if (ret) > > > > > > > > > > + return dev_err_probe(dev, ret, > > > > > > > > > > + "failed to get clock frequency"); > > > > > > > > > > + } > > > > > > > > > > + > > > > > > > > > > > > > > > > > > This doesn't seem specific to the imx219 driver. Could you turn this > > > > > > > > > into a generic V4L2 sensor helper that would take a struct device and a > > > > > > > > > clock name, and return the frequency, either retrieved from the clock, > > > > > > > > > or from the clock-frequency property as a fallback ? > > > > > > > > > > > > > > > > > > Some drivers will also need to control the clock, so the clock should > > > > > > > > > probably be returned too. > > > > > > > > > > > > > > > > > > > > > > > > > Yes, I saw that many sensor drivers have the same issue. > > > > > > > > > > > > > > > > I will try to make it into a generic V4L2 helper and send the patches. > > > > > > > > > > > > > > There are other such functions in drivers/media/v4l2-core/v4l2-common.c. > > > > > > > Perhaps this is where the new helper could be located as well? > > > > > > > > > > > > > > > > > > > I was thinking about drivers/media/v4l2-core/v4l2-fwnode.c but if > > > > > > v4l2-common.c is more appropriate we can go with that. > > > > > > > > > > I admit I have no clue about ACPI, but why is this v4l2 specific? Why > > > > > doesn't clock framework do this for us? > > > > > > > > The "clock-frequency" isn't really specific to ACPI but it's used on some > > > > boards with DT, too, that precede the current clock bindings. Clocks aren't > > > > generally available to OS in ACPI either but the sensor drivers still need > > > > them. DisCo for Imaging uses "mipi-img-clock-frequency" which DisCo for > > > > Imaging code deep down in the ACPI framework will offer to drivers as > > > > "clock-frequency". A lot of this is actually specific to cameras. On top of > > > > that, camera sensors tend to be devices that are used equally on both DT > > > > and ACPI systems, it's quite uncommon elsewhere. Therefore I do think the > > > > natural place for this code is actually the V4L2 framework. > > > > > > Can ACPI devices support programmable sensor clock frequency ? > > > > Do you mean sensor's external clock or PLL? And do you mean programmable > > as configured in system firmware or at runtime? > > I mean external clock, and configurable at runtime. There's basically no standard API to change a clock's frequency at runtime (as there is no API to handle clocks) -- which is why we have a property instead of that presumed API. -- Regards, Sakari Ailus