From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices Date: Tue, 4 Jul 2017 14:47:48 +0200 Message-ID: <8ca5511a-b56c-d5b9-bf37-61fb7c293c0e@redhat.com> References: <20170704124613.14591-1-hdegoede@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:45828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751645AbdGDMrv (ORCPT ); Tue, 4 Jul 2017 08:47:51 -0400 In-Reply-To: <20170704124613.14591-1-hdegoede@redhat.com> Content-Language: en-US Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Jarkko Nikula , Wolfram Sang , Len Brown , Andy Shevchenko , Mika Westerberg Cc: linux-i2c@vger.kernel.org Hi all, I forgot to add "v2" to the subject, but this is a rebased v2, which should apply cleanly on next. Regards. Hans On 04-07-17 14:46, 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. > > Signed-off-by: Hans de Goede > --- > Changes in v2: > -Rebase on top of linux-i2c/for-next > --- > drivers/i2c/i2c-core-acpi.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c > index 052005579ed6..bda281293d28 100644 > --- a/drivers/i2c/i2c-core-acpi.c > +++ b/drivers/i2c/i2c-core-acpi.c > @@ -82,11 +82,22 @@ 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); > >