From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v2] i2c: of: Try to find an I2C adapter matching the parent Date: Mon, 28 Jan 2019 09:08:15 +0100 Message-ID: <20190128080815.GD18124@ulmo> References: <20190125131142.26837-1-thierry.reding@gmail.com> <844544bc-10ac-a236-8c7d-17a09288fe5d@gmx.de> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1651563139==" Return-path: In-Reply-To: <844544bc-10ac-a236-8c7d-17a09288fe5d@gmx.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Tristan Bastian Cc: Wolfram Sang , Vlado Plaga , dri-devel@lists.freedesktop.org, Rob Herring , linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org List-Id: linux-i2c@vger.kernel.org --===============1651563139== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="YToU2i3Vx8H2dn7O" Content-Disposition: inline --YToU2i3Vx8H2dn7O Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jan 26, 2019 at 01:37:34PM +0100, Tristan Bastian wrote: > Am 25.01.19 um 14:11 schrieb Thierry Reding: > > From: Thierry Reding > >=20 > > If an I2C adapter doesn't match the provided device tree node, also try > > matching the parent's device tree node. This allows finding an adapter > > based on the device node of the parent device that was used to register > > it. > >=20 > > This fixes a regression on Tegra124-based Chromebooks (Nyan) where the > > eDP controller registers an I2C adapter that is used to read to EDID. > > After commit 993a815dcbb2 ("dt-bindings: panel: Add missing .txt > > suffix") this stopped working because the I2C adapter could no longer > > be found. The approach in this patch fixes the regression without > > introducing the issues that the above commit solved. > >=20 > > Fixes: 17ab7806de0c ("drm: don't link DP aux i2c adapter to the hardwar= e device node") > > Signed-off-by: Thierry Reding > > --- > > Changes in v2: > > - check for both device and parent device tree nodes for each device > > instead of looping through the list of devices twice > >=20 > > drivers/i2c/i2c-core-of.c | 14 +++++++++++++- > > 1 file changed, 13 insertions(+), 1 deletion(-) > >=20 > > diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c > > index 6cb7ad608bcd..0f01cdba9d2c 100644 > > --- a/drivers/i2c/i2c-core-of.c > > +++ b/drivers/i2c/i2c-core-of.c > > @@ -121,6 +121,17 @@ static int of_dev_node_match(struct device *dev, v= oid *data) > > return dev->of_node =3D=3D data; > > } > > +static int of_dev_or_parent_node_match(struct device *dev, void *data) > > +{ > > + if (dev->of_node =3D=3D data) > > + return 1; > > + > > + if (dev->parent) > > + return dev->parent->of_node =3D=3D data; > > + > > + return 0; > > +} > > + > > /* must call put_device() when done with returned i2c_client device */ > > struct i2c_client *of_find_i2c_device_by_node(struct device_node *nod= e) > > { > > @@ -145,7 +156,8 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(str= uct device_node *node) > > struct device *dev; > > struct i2c_adapter *adapter; > > - dev =3D bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match); > > + dev =3D bus_find_device(&i2c_bus_type, NULL, node, > > + of_dev_or_parent_node_match); > > if (!dev) > > return NULL; >=20 > I've tested this and can confirm that this fixes the issue on the nyan-big > chromebook. Excellent, thanks for testing! Typically if you've tested a patch and verified that it fixes the problem that you were seeing, it's good to send this on a line by itself along with your reply: Tested-by: Tristan Bastian Patchwork will pick this up and it will become part of the commit message when the patch is applied. This gives you the credit you deserve for going through the trouble of testing the change. > Is this fix going to be applied to the LTS kernels too? The "Fixes:" line in the commit message should ensure that this does get backported to relevant stable kernels. 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