Re: [PATCH][drivers/misc/thinkpad_acpi.c] duplicate test if (level & TP_EC_FAN_FULLSPEED)

Roel Kluin
2008-02-05T08:35:20Z

Henrique de Moraes Holschuh wrote:
> On Tue, 05 Feb 2008, Roel Kluin wrote:
>> Roland Dreier wrote:
>>> > /* safety net should the EC not support AUTO
>>> > * or FULLSPEED mode bits and just ignore them */
>>> > if (level & TP_EC_FAN_FULLSPEED)
>>> > level |= 7; /* safety min speed 7 */
>>> > else if (level & TP_EC_FAN_FULLSPEED)
>>> > level |= 4; /* safety min speed 4 */
>>> >
>>> > Note the duplicate test 'if (level & TP_EC_FAN_FULLSPEED)'. should
>>> > this be replaced by
>>>
>>> Actually I suspect one of the two tests should be against TP_EC_FAN_AUTO
>>> (based on the comment).
>> Thanks Roland, for your info
>>
>> based on the comments in commit eaa7571b2d1a08873e4bdd8e6db3431df61cd9ad,
>> I think this should be modified like below:
>>
>> ACPI: thinkpad-acpi: add a safety net for TPEC fan control mode
>> The Linux ThinkPad community is not positive that all ThinkPads that do
>> HFSP EC fan control do implement full-speed and auto modes, some of the
>> earlier ones supporting HFSP might not.
>>
>> If the EC ignores the AUTO or FULL-SPEED bits, it will pay attention to the
>> lower three bits that set the fan level. And as thinkpad-acpi was leaving
>> these set to zero, it would stop(!) the fan, which is Not A Good Thing.
>> So, as a safety net, we now make sure to also set the fan level part of the
>> HFSP register to speed 7 for full-speed, and a minimum of speed 4 for auto
>> mode.
>> --
>> second TP_EC_FAN_FULLSPEED should be P_EC_FAN_AUTO
>>
>>
>> Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
>> ---
>> diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
>> index cf56647..3c323fe 100644
>> --- a/drivers/misc/thinkpad_acpi.c
>> +++ b/drivers/misc/thinkpad_acpi.c
>> @@ -4138,7 +4138,7 @@ static int fan_set_level(int level)
>> * or FULLSPEED mode bits and just ignore them */
>> if (level & TP_EC_FAN_FULLSPEED)
>> level |= 7; /* safety min speed 7 */
>> - else if (level & TP_EC_FAN_FULLSPEED)
>> + else if (level & TP_EC_FAN_AUTO)
>> level |= 4; /* safety min speed 4 */
>>
>> if (!acpi_ec_write(fan_status_offset, level))
>
> ACK. This needs to be sent to stable as well. I think both 2.6.22 and
> 2.6.23 need this patch.
>

CC stable@kernel.org