From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices Date: Mon, 03 Jul 2017 14:10:12 +0300 Message-ID: <1499080212.22624.237.camel@linux.intel.com> References: <20170701100311.11859-1-hdegoede@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: Received: from mga14.intel.com ([192.55.52.115]:60588 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753126AbdGCLKQ (ORCPT ); Mon, 3 Jul 2017 07:10:16 -0400 In-Reply-To: <20170701100311.11859-1-hdegoede@redhat.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Hans de Goede , Jarkko Nikula , Wolfram Sang , Len Brown , Mika Westerberg Cc: linux-i2c@vger.kernel.org On Sat, 2017-07-01 at 12:03 +0200, Hans de Goede wrote: > ACPI video devices get tagged by the kernel with the custom LNXVIDEO > HID so that normal pnp-id matching can be used and are handled by the > acpi-video driver. > > Sometimes the ACPI nodes describing these contain a SERIAL_TYPE_I2C > ACPI > resource. Before this commit the presence of this resource would cause > the > i2c-core to create a /sys/bus/i2c/devices/i2c-LNXVIDEO:00 device for > this > with a modalias of: "i2c:LNXVIDEO:00". > > There is no i2c driver for this custom HID, the acpi-video driver > binds > directly to the ACPI device /sys/bus/acpi/devices/LNXVIDEO\:00 which > has > a modalias of "acpi:LNXVIDEO:" . > > Not only is the creation of an i2c-client for this undesirable, it is > actually causing problems. This weird pseudo-resource claims an i2c > speed of 100KHz and typically points to the i2c bus which is used by > the > touchscreen controller. Some touchscreen controllers only work > properly at > 400KHz, at 100KHz they cause errors like these: > > i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration > i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration > i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration > i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration > silead_ts i2c-MSSL1680:00: Registers clear error -11 > > This commit makes the i2c-core ignore LNXVIDEO compatible ACPI devices > which has 2 positive results: > > 1) The bogus i2c-client for these is no longer created. > 2) i2c_acpi_lookup_speed now ignores the 100KHz speed from the pseudo > i2c-resouce and properly returns 400KHz as speed for the touchscreen > i2c bus, fixing the touchscreen not working on various devies. Should it have Fixes tag? > > Signed-off-by: Hans de Goede > --- >  drivers/i2c/i2c-core.c | 11 +++++++++++ Shouldn't you rebase it on top of i2c-next? The file is called i2c-core- acpi.c nowadays. >  1 file changed, 11 insertions(+) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 82576aaccc90..4334ee1116fe 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -154,11 +154,22 @@ static int i2c_acpi_do_lookup(struct acpi_device > *adev, >   struct i2c_board_info *info = lookup->info; >   struct list_head resource_list; >   int ret; > + static const struct acpi_device_id video_device_ids[] = { > + { ACPI_VIDEO_HID, 0 }, > + {} > + }; >   >   if (acpi_bus_get_status(adev) || !adev->status.present || >       acpi_device_enumerated(adev)) >   return -EINVAL; >   > + /* > +  * ACPI video acpi_devices, which are handled by the acpi- > video driver > +  * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore > these. > +  */ > + if (acpi_match_device_ids(adev, video_device_ids) == 0) > + return -ENODEV; > + >   memset(info, 0, sizeof(*info)); >   lookup->device_handle = acpi_device_handle(adev); >   -- Andy Shevchenko Intel Finland Oy