[PATCH] platform/x86: thinkpad_acpi: Correct thermal sensor allocation

[PATCH] platform/x86: thinkpad_acpi: Correct thermal sensor allocation

[Mark Pearson]

On recent Thinkpad platforms it was reported that temp sensor 11 was
always incorrectly displaying 66C. It turns out the reason for this is
that this location in EC RAM is not a temperature sensor but is the
power supply ID (offset 0xC2).

Based on feedback from the Lenovo firmware team the EC RAM version can
be determined and for the current version (3) only the 0x78 to 0x7F
range is used for temp sensors. I don't have any details for earlier
versions so I have left the implementation unaltered there.

Note - in this block only 0x78 and 0x79 are officially designated (CPU &
GPU sensors). The use of the other locations in the block will vary from
platform to platform; but the existing logic to detect a sensor presence
holds.

Signed-off-by: Mark Pearson <markpearson@lenovo.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 31 ++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 07de21941..8fbe4d3d9 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6260,6 +6260,7 @@ enum thermal_access_mode {
 enum { /* TPACPI_THERMAL_TPEC_* */
 	TP_EC_THERMAL_TMP0 = 0x78,	/* ACPI EC regs TMP 0..7 */
 	TP_EC_THERMAL_TMP8 = 0xC0,	/* ACPI EC regs TMP 8..15 */
+	TP_EC_FUNCREV      = 0xEF,      /* ACPI EC Functional revision */
 	TP_EC_THERMAL_TMP_NA = -128,	/* ACPI EC sensor not available */
 
 	TPACPI_THERMAL_SENSOR_NA = -128000, /* Sensor not available */
@@ -6458,7 +6459,7 @@ static const struct attribute_group thermal_temp_input8_group = {
 
 static int __init thermal_init(struct ibm_init_struct *iibm)
 {
-	u8 t, ta1, ta2;
+	u8 t, ta1, ta2, ver;
 	int i;
 	int acpi_tmp7;
 	int res;
@@ -6473,7 +6474,14 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
 		 * 0x78-0x7F, 0xC0-0xC7.  Registers return 0x00 for
 		 * non-implemented, thermal sensors return 0x80 when
 		 * not available
+		 * The above rule is unfortunately flawed. This has been seen with
+		 * 0xC2 (power supply ID) causing thermal control problems.
+		 * The EC version can be determined by offset 0xEF and at least for
+		 * version 3 the Lenovo firmware team confirmed that registers 0xC0-0xC7
+		 * are not thermal registers.
 		 */
+		if (!acpi_ec_read(TP_EC_FUNCREV, &ver))
+			pr_warn("Thinkpad ACPI EC unable to access EC version\n");
 
 		ta1 = ta2 = 0;
 		for (i = 0; i < 8; i++) {
@@ -6483,11 +6491,13 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
 				ta1 = 0;
 				break;
 			}
-			if (acpi_ec_read(TP_EC_THERMAL_TMP8 + i, &t)) {
-				ta2 |= t;
-			} else {
-				ta1 = 0;
-				break;
+			if (ver < 3) {
+				if (acpi_ec_read(TP_EC_THERMAL_TMP8 + i, &t)) {
+					ta2 |= t;
+				} else {
+					ta1 = 0;
+					break;
+				}
 			}
 		}
 		if (ta1 == 0) {
@@ -6500,9 +6510,12 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
 				thermal_read_mode = TPACPI_THERMAL_NONE;
 			}
 		} else {
-			thermal_read_mode =
-			    (ta2 != 0) ?
-			    TPACPI_THERMAL_TPEC_16 : TPACPI_THERMAL_TPEC_8;
+			if (ver >= 3)
+				thermal_read_mode = TPACPI_THERMAL_TPEC_8;
+			else
+				thermal_read_mode =
+					(ta2 != 0) ?
+					TPACPI_THERMAL_TPEC_16 : TPACPI_THERMAL_TPEC_8;
 		}
 	} else if (acpi_tmp7) {
 		if (tpacpi_is_ibm() &&
-- 
2.30.2

Re: [PATCH] platform/x86: thinkpad_acpi: Correct thermal sensor allocation

[Hans de Goede]

Hi,

On 4/7/21 11:20 PM, Mark Pearson wrote:
> On recent Thinkpad platforms it was reported that temp sensor 11 was
> always incorrectly displaying 66C. It turns out the reason for this is
> that this location in EC RAM is not a temperature sensor but is the
> power supply ID (offset 0xC2).
> 
> Based on feedback from the Lenovo firmware team the EC RAM version can
> be determined and for the current version (3) only the 0x78 to 0x7F
> range is used for temp sensors. I don't have any details for earlier
> versions so I have left the implementation unaltered there.
> 
> Note - in this block only 0x78 and 0x79 are officially designated (CPU &
> GPU sensors). The use of the other locations in the block will vary from
> platform to platform; but the existing logic to detect a sensor presence
> holds.
> 
> Signed-off-by: Mark Pearson <markpearson@lenovo.com>

I've merged this, note I've added one small fixup to initialize ver to
0 when it is declared, also see a remark inline below.

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.


> ---
>  drivers/platform/x86/thinkpad_acpi.c | 31 ++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 07de21941..8fbe4d3d9 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -6260,6 +6260,7 @@ enum thermal_access_mode {
>  enum { /* TPACPI_THERMAL_TPEC_* */
>  	TP_EC_THERMAL_TMP0 = 0x78,	/* ACPI EC regs TMP 0..7 */
>  	TP_EC_THERMAL_TMP8 = 0xC0,	/* ACPI EC regs TMP 8..15 */
> +	TP_EC_FUNCREV      = 0xEF,      /* ACPI EC Functional revision */
>  	TP_EC_THERMAL_TMP_NA = -128,	/* ACPI EC sensor not available */
>  
>  	TPACPI_THERMAL_SENSOR_NA = -128000, /* Sensor not available */
> @@ -6458,7 +6459,7 @@ static const struct attribute_group thermal_temp_input8_group = {
>  
>  static int __init thermal_init(struct ibm_init_struct *iibm)
>  {
> -	u8 t, ta1, ta2;
> +	u8 t, ta1, ta2, ver;
>  	int i;
>  	int acpi_tmp7;
>  	int res;
> @@ -6473,7 +6474,14 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
>  		 * 0x78-0x7F, 0xC0-0xC7.  Registers return 0x00 for
>  		 * non-implemented, thermal sensors return 0x80 when
>  		 * not available
> +		 * The above rule is unfortunately flawed. This has been seen with
> +		 * 0xC2 (power supply ID) causing thermal control problems.
> +		 * The EC version can be determined by offset 0xEF and at least for
> +		 * version 3 the Lenovo firmware team confirmed that registers 0xC0-0xC7
> +		 * are not thermal registers.
>  		 */
> +		if (!acpi_ec_read(TP_EC_FUNCREV, &ver))
> +			pr_warn("Thinkpad ACPI EC unable to access EC version\n");

So what happens with ver in case the pr_warn here triggers?

As said above I've added a small change to initialize ver to 0 when declared,
so that we keep the old behavior when this pr_warn triggers.

>  
>  		ta1 = ta2 = 0;
>  		for (i = 0; i < 8; i++) {
> @@ -6483,11 +6491,13 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
>  				ta1 = 0;
>  				break;
>  			}
> -			if (acpi_ec_read(TP_EC_THERMAL_TMP8 + i, &t)) {
> -				ta2 |= t;
> -			} else {
> -				ta1 = 0;
> -				break;
> +			if (ver < 3) {
> +				if (acpi_ec_read(TP_EC_THERMAL_TMP8 + i, &t)) {
> +					ta2 |= t;
> +				} else {
> +					ta1 = 0;
> +					break;
> +				}
>  			}
>  		}
>  		if (ta1 == 0) {
> @@ -6500,9 +6510,12 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
>  				thermal_read_mode = TPACPI_THERMAL_NONE;
>  			}
>  		} else {
> -			thermal_read_mode =
> -			    (ta2 != 0) ?
> -			    TPACPI_THERMAL_TPEC_16 : TPACPI_THERMAL_TPEC_8;
> +			if (ver >= 3)
> +				thermal_read_mode = TPACPI_THERMAL_TPEC_8;
> +			else
> +				thermal_read_mode =
> +					(ta2 != 0) ?
> +					TPACPI_THERMAL_TPEC_16 : TPACPI_THERMAL_TPEC_8;
>  		}
>  	} else if (acpi_tmp7) {
>  		if (tpacpi_is_ibm() &&
> 

Regards,

Hans

Re: [External] Re: [PATCH] platform/x86: thinkpad_acpi: Correct thermal sensor allocation

[Mark Pearson]

Thanks Hans

On 13/04/2021 02:28, Hans de Goede wrote:
> Hi,
> 
> On 4/7/21 11:20 PM, Mark Pearson wrote:
>> On recent Thinkpad platforms it was reported that temp sensor 11 was
>> always incorrectly displaying 66C. It turns out the reason for this is
>> that this location in EC RAM is not a temperature sensor but is the
>> power supply ID (offset 0xC2).
>>
>> Based on feedback from the Lenovo firmware team the EC RAM version can
>> be determined and for the current version (3) only the 0x78 to 0x7F
>> range is used for temp sensors. I don't have any details for earlier
>> versions so I have left the implementation unaltered there.
>>
>> Note - in this block only 0x78 and 0x79 are officially designated (CPU &
>> GPU sensors). The use of the other locations in the block will vary from
>> platform to platform; but the existing logic to detect a sensor presence
>> holds.
>>
>> Signed-off-by: Mark Pearson <markpearson@lenovo.com>
> 
> I've merged this, note I've added one small fixup to initialize ver to
> 0 when it is declared, also see a remark inline below.
> 

Agreed on setting ver to zero - thanks for adding that

Mark