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smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=Pyz0Hz7W; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="Pyz0Hz7W" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 1B59C455; Mon, 24 Feb 2025 14:24:28 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1740403468; bh=dxn2Ivz1g48euPARZzhOWf+gknPeRL78i4fC9lcRQA8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Pyz0Hz7WZ7pBeAP2opzqXFUepi3f2MGqeDTIXIUyCnaliMBCR3iluVRP4xgIhcs4l xKR2gDkyF28kJpGTkE4L+jkMo6//92sBrpd5iZzqsVYzonWMWZHeHVTkDkkzxLlzLm og18xN/Gw1kTFVUa3fpVqoygEiKcKYgT+Oy55kWo= Date: Mon, 24 Feb 2025 15:25:36 +0200 From: Laurent Pinchart To: Sakari Ailus Cc: Tomi Valkeinen , Mehdi Djait , dave.stevenson@raspberrypi.com, linux-media@vger.kernel.org Subject: Re: [PATCH] media: i2c: imx219: Add support for 'clock-frequency' parsing Message-ID: <20250224132536.GE25447@pendragon.ideasonboard.com> References: <20250220154909.152538-1-mehdi.djait@linux.intel.com> <20250223230649.GD16159@pendragon.ideasonboard.com> <2462254c-bd3f-488b-94d9-e11e16108327@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 ? -- Regards, Laurent Pinchart