Re: [PATCH v3 resend 3/3] mmc: sdhci-acpi: Add DMI based blacklist

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 08-06-17 12:20, Hans de Goede wrote:
> Hi,
> 
> On 07-06-17 15:09, Adrian Hunter wrote:
>> On 24/05/17 13:47, Hans de Goede wrote:
>>> Add a DMI based blacklist for systems where probing some sdio interfaces
>>> is harmful (e.g. causes pci-e based wifi to not work).
>>>
>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>>> ---
>>> Changes in v2:
>>> -Adjust for changes in mmc: sdhci-acpi: Add fix_up_power_blacklist module option
>>> -Only use a single fix_up_power_dmi_blacklist for the GPDwin further testing
>>>   has shown that the DMI strings are unique enough that we do not need the
>>>   bios-date in there
>>> Changes in v3:
>>> -Adjust for changes to "mmc: sdhci-acpi: Add blacklist module option"
>>> ---
>>>   drivers/mmc/host/sdhci-acpi.c | 30 ++++++++++++++++++++++++++++++
>>>   1 file changed, 30 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
>>> index 3a7d979a306d..45455abc7ca6 100644
>>> --- a/drivers/mmc/host/sdhci-acpi.c
>>> +++ b/drivers/mmc/host/sdhci-acpi.c
>>> @@ -36,6 +36,7 @@
>>>   #include <linux/pm.h>
>>>   #include <linux/pm_runtime.h>
>>>   #include <linux/delay.h>
>>> +#include <linux/dmi.h>
>>>   #include <linux/mmc/host.h>
>>>   #include <linux/mmc/pm.h>
>>> @@ -381,6 +382,28 @@ static const struct acpi_device_id sdhci_acpi_ids[] = {
>>>   };
>>>   MODULE_DEVICE_TABLE(acpi, sdhci_acpi_ids);
>>> +static const struct dmi_system_id fix_up_power_dmi_blacklist[] = {
>>> +    {
>>> +        /*
>>> +         * Match for the GPDwin which unfortunately uses somewhat
>>> +         * generic dmi strings, which is why we test for 4 strings.
>>> +         * Comparing against 23 other byt/cht boards, board_vendor
>>> +         * and board_name are unique to the GPDwin, where as only one
>>> +         * other board has the same board_serial and 3 others have
>>> +         * the same default product_name. Also the GPDwin is the
>>> +         * only device to have both board_ and product_name not set.
>>> +         */
>>> +        .driver_data = "80860F14:2",
>>> +        .matches = {
>>> +            DMI_MATCH(DMI_BOARD_VENDOR, "AMI Corporation"),
>>> +            DMI_MATCH(DMI_BOARD_NAME, "Default string"),
>>> +            DMI_MATCH(DMI_BOARD_SERIAL, "Default string"),
>>> +            DMI_MATCH(DMI_PRODUCT_NAME, "Default string"),
>>
>> I can't accept that this is an accurate way to identify the board.
> 
> Well as I already mentioned when I first submitted this patch-set this
> patch-set fixes a regression. When I first installed Linux on this
> system, the wifi just worked, until this commit got merged:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=db52d4f8a4bde36263a7cc9d46ff20b243562ac9
> 
> Given the kernel's no regressions policy I see only 2 ways to fix this
> something like this patch, or revert the commit causing the regression.
> 
> In the CHT dstd's I have 6 out of 8 use the 80860F14 HID rather then
> the INT33BB HID one, so reverting the commit causing this regression
> is not really an option.
> 
> Note that the quirk not only matches on DMI strings, but also on the
> 80860F14:2 pair, further narrowing the chance for duplicate matches.
> 
> I've access to 29 dmi dumps of Bay / Cherry Trail tablets now and
> only 3 match DMI_MATCH(DMI_BOARD_VENDOR, "AMI Corporation") (*),
> and only 1 out of 29 (the GPD win) matches DMI_MATCH(DMI_BOARD_NAME,
> "Default string") so after 2 of the 5 checks (including the UID
> check) we already have only the GPD win matching.

So thinking more about this, one more thing which can be done to
make sure the dmi match is unique to the GPD win is also check
the BIOS date, as I did in v1 of this patch set, one problem with
that is that the manufacturer does tend to update the BIOS date in
new production batches (*) and I ended up with many classic
dmi table entries which were all identical except for the bios_date
field. So for v4 I've coded out the bios-date check as a separate
check so that we can have an array of bios-dates for a single
dmi quirk table entry.

Regards,

Hans

*) I've notified them of the BIOS bug and asked them to fix this
(as well as provide better dmi strings) they have acknowledged receipt
of my email and said they would forward it to their engineers, so
this may get fixed in a later version at which point we don't need
to add the dates of the fixed and newer bios versions.