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    Subject[PATCH 4.9 006/240] platform/x86: thinkpad_acpi: Correct thermal sensor allocation
    Date
    From: Mark Pearson <markpearson@lenovo.com>

    commit 6759e18e5cd8745a5dfc5726e4a3db5281ec1639 upstream.

    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>
    Link: https://lore.kernel.org/r/20210407212015.298222-1-markpearson@lenovo.com
    Reviewed-by: Hans de Goede <hdegoede@redhat.com>
    Signed-off-by: Hans de Goede <hdegoede@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/platform/x86/thinkpad_acpi.c | 31 ++++++++++++++++++++++---------
    1 file changed, 22 insertions(+), 9 deletions(-)

    --- a/drivers/platform/x86/thinkpad_acpi.c
    +++ b/drivers/platform/x86/thinkpad_acpi.c
    @@ -6044,6 +6044,7 @@ 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 */
    @@ -6242,7 +6243,7 @@ static const struct attribute_group ther

    static int __init thermal_init(struct ibm_init_struct *iibm)
    {
    - u8 t, ta1, ta2;
    + u8 t, ta1, ta2, ver = 0;
    int i;
    int acpi_tmp7;
    int res;
    @@ -6257,7 +6258,14 @@ static int __init thermal_init(struct ib
    * 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++) {
    @@ -6267,11 +6275,13 @@ static int __init thermal_init(struct ib
    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) {
    @@ -6287,9 +6297,12 @@ static int __init thermal_init(struct ib
    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() &&

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