From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH v2] i2c: i2c-scmi: add a MS HID Date: Wed, 5 Apr 2017 14:59:32 +0200 Message-ID: <20170405145932.3ef689d5@endymion> References: <1491322707-2991-1-git-send-email-vkrasnov@dev.rtsoft.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de ([195.135.220.15]:33136 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932597AbdDEM7g (ORCPT ); Wed, 5 Apr 2017 08:59:36 -0400 In-Reply-To: <1491322707-2991-1-git-send-email-vkrasnov@dev.rtsoft.ru> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Viktor Krasnov Cc: wsa@the-dreams.de, linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, mika.westerberg@linux.intel.com, andriy.shevchenko@linux.intel.com, jarkko.nikula@linux.intel.com, echerkasov@dev.rtsoft.ru, Michael.Brunner@kontron.com On Tue, 4 Apr 2017 19:18:27 +0300, Viktor Krasnov wrote: > From: Edgar Cherkasov > > Description of the problem: > - i2c-scmi driver contains only two identifiers "SMBUS01" and "SMBUSIBM"; > - the fist HID (SMBUS01) is clearly defined in "SMBus Control Method > Interface Specification, version 1.0": "Each device must specify > 'SMBUS01' as its _HID and use a unique _UID value"; > - unfortunately, BIOS vendors (like AMI) seem to ignore this requirement > and implement "SMB0001" HID instead of "SMBUS01"; > - I speculate that they do this because only "SMB0001" is hard coded in > Windows SMBus driver produced by Microsoft. > > This leads to following situation: > - SMBus works out of box in Windows but not in Linux; > - board vendors are forced to add correct "SMBUS01" HID to BIOS to make > SMBus work in Linux. Moreover the same board vendors complain that > tools (3-rd party ASL compiler) do not like the "SMBUS01" identifier > and produce errors. So they need to constantly patch the compiler for > each new version of BIOS. > > As it is very unlikely that BIOS vendors implement a correct HID in > future, I would propose to consider whether it is possible to work around > the problem by adding MS HID to the Linux i2c-scmi driver. > > v2: move the definition of the new HID to the driver itself. > > Signed-off-by: Edgar Cherkasov > Signed-off-by: Michael Brunner > Acked-by: Viktor Krasnov Reviewed-by: Jean Delvare > --- > drivers/i2c/busses/i2c-scmi.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-scmi.c b/drivers/i2c/busses/i2c-scmi.c > index dfc98df..f876dd6 100644 > --- a/drivers/i2c/busses/i2c-scmi.c > +++ b/drivers/i2c/busses/i2c-scmi.c > @@ -18,6 +18,9 @@ > #define ACPI_SMBUS_HC_CLASS "smbus" > #define ACPI_SMBUS_HC_DEVICE_NAME "cmi" > > +/* SMBUS HID definition as supported by Microsoft Windows */ > +#define ACPI_SMBUS_MS_HID "SMB0001" > + > ACPI_MODULE_NAME("smbus_cmi"); > > struct smbus_methods_t { > @@ -51,6 +54,7 @@ struct acpi_smbus_cmi { > static const struct acpi_device_id acpi_smbus_cmi_ids[] = { > {"SMBUS01", (kernel_ulong_t)&smbus_methods}, > {ACPI_SMBUS_IBM_HID, (kernel_ulong_t)&ibm_smbus_methods}, > + {ACPI_SMBUS_MS_HID, (kernel_ulong_t)&smbus_methods}, > {"", 0} > }; > MODULE_DEVICE_TABLE(acpi, acpi_smbus_cmi_ids); -- Jean Delvare SUSE L3 Support