> -----Original Message-----
> From: Nilawar, Badal <badal.nilawar@xxxxxxxxx>
> Sent: Monday, October 16, 2023 1:03 PM
> To: Gupta, Anshuman <anshuman.gupta@xxxxxxxxx>; intel-
> xe@xxxxxxxxxxxxxxxxxxxxx; linux-hwmon@xxxxxxxxxxxxxxx
> Cc: Dixit, Ashutosh <ashutosh.dixit@xxxxxxxxx>; andi.shyti@xxxxxxxxxxxxxxx;
> Tauro, Riana <riana.tauro@xxxxxxxxx>; Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>
> Subject: Re: [PATCH 1/2] drm/xe/hwmon: Protect hwmon rw attributes with
> hwmon_lock
>
> Hi Anshuman,
>
> On 09-10-2023 19:06, Gupta, Anshuman wrote:
> >
> >
> > On 10/6/2023 10:32 PM, Badal Nilawar wrote:
> >> Take hwmon_lock while accessing hwmon rw attributes. For readonly
> >> attributes its not required to take lock as reads are protected by
> >> sysfs layer and therefore sequential.
> >>
> >> Cc: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>
> >> Cc: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
> >> Signed-off-by: Badal Nilawar <badal.nilawar@xxxxxxxxx>
> >> ---
> >> drivers/gpu/drm/xe/xe_hwmon.c | 143
> >> +++++++++++++++++-----------------
> >> 1 file changed, 71 insertions(+), 72 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c
> >> b/drivers/gpu/drm/xe/xe_hwmon.c index 9ac05994a967..391f9a8dd9d7
> >> 100644
> >> --- a/drivers/gpu/drm/xe/xe_hwmon.c
> >> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> >> @@ -47,7 +47,7 @@ struct xe_hwmon_energy_info {
> >> struct xe_hwmon {
> >> struct device *hwmon_dev;
> >> struct xe_gt *gt;
> >> - struct mutex hwmon_lock; /* rmw operations*/
> >> + struct mutex hwmon_lock; /* For rw attributes */
> >> int scl_shift_power;
> >> int scl_shift_energy;
> >> struct xe_hwmon_energy_info ei; /* Energy info for
> >> energy1_input */ @@ -95,47 +95,45 @@ static u32
> >> xe_hwmon_get_reg(struct xe_hwmon *hwmon, enum xe_hwmon_reg
> hwmon_reg)
> >> return reg.raw;
> >> }
> >> -static int xe_hwmon_process_reg(struct xe_hwmon *hwmon, enum
> >> xe_hwmon_reg hwmon_reg,
> >> - enum xe_hwmon_reg_operation operation, u32 *value,
> >> - u32 clr, u32 set)
> >> +static void xe_hwmon_process_reg(struct xe_hwmon *hwmon, enum
> >> xe_hwmon_reg hwmon_reg,
> >> + enum xe_hwmon_reg_operation operation, u32 *value,
> >> + u32 clr, u32 set)
> >> {
> >> struct xe_reg reg;
> >> reg.raw = xe_hwmon_get_reg(hwmon, hwmon_reg);
> >> if (!reg.raw)
> >> - return -EOPNOTSUPP;
> >> + return;
> > Don't we need to report this as warning?
> > What is possiblity of code path landing here.
> Warning is added in xe_hwmon_get_reg when reg is invalid. Warning is not
> needed when reg is not supported by platform. During runtime code path will
> not fall here as visible functions are taking care of creating hwmon entries only
> if regs are supported. So it doesn't make sense to add warn here.
> >> switch (operation) {
> >> case REG_READ:
> >> *value = xe_mmio_read32(hwmon->gt, reg);
> >> - return 0;
> >> + break;
> >> case REG_WRITE:
> >> xe_mmio_write32(hwmon->gt, reg, *value);
> >> - return 0;
> >> + break;
> >> case REG_RMW:
> >> *value = xe_mmio_rmw32(hwmon->gt, reg, clr, set);
> >> - return 0;
> >> + break;
> >> default:
> >> drm_warn(>_to_xe(hwmon->gt)->drm, "Invalid xe hwmon reg
> >> operation: %d\n",
> >> operation);
> >> - return -EOPNOTSUPP;
> >> + break;
> >> }
> >> }
> >> -static int xe_hwmon_process_reg_read64(struct xe_hwmon *hwmon,
> >> - enum xe_hwmon_reg hwmon_reg, u64 *value)
> >> +static void xe_hwmon_process_reg_read64(struct xe_hwmon *hwmon,
> >> + enum xe_hwmon_reg hwmon_reg, u64 *value)Isn't it
> >> possible to pass len of void * value to xe_hwmon_process_reg()
> > so we can wrap this fucntion in xe_hwmon_process_reg ?
> Yes its possible but I feel it would be more useful if there are regs of variable
> lengths i.e. other than 64 or 32 bit. As of now hwmon regs are
> 32 and 64 bit lenghts so I prefered 2 separate functions. If you insist I will
> wrap.
Another thing do we have any consumer of REG_WRITE, I don't see any caller (it is a dead code), considering above there is no real benefit of keeping the abstraction with
xe_hwmon_process_reg() and hwmon_process_reg_read64(). If keeping hwmon_process_reg_read64() is simple then it is defeating the purpose of
xe_hwmon_process_reg().
IMHO the only benefit xe_hwmon_process_reg() provides scalability for future platforms like forcewake is needed,
if intention is to keep it simple then Calling xe_mmio_{read32, read64_2x32, xe_mmio_rmw32} directly is much simpler than having multiple wrappers ?
Br,
Anshuman Gupta.
>
> Regards,
> Badal
> >
> >> {
> >> struct xe_reg reg;
> >> reg.raw = xe_hwmon_get_reg(hwmon, hwmon_reg);
> >> if (!reg.raw)
> >> - return -EOPNOTSUPP;
> >> + return;
> >> *value = xe_mmio_read64_2x32(hwmon->gt, reg);
> >> -
> >> - return 0;
> >> }
> >> #define PL1_DISABLE 0
> >> @@ -146,16 +144,18 @@ static int
> xe_hwmon_process_reg_read64(struct
> >> xe_hwmon *hwmon,
> >> * same pattern for sysfs, allow arbitrary PL1 limits to be set but
> >> display
> >> * clamped values when read.
> >> */
> >> -static int xe_hwmon_power_max_read(struct xe_hwmon *hwmon, long
> >> *value)
> >> +static void xe_hwmon_power_max_read(struct xe_hwmon *hwmon, long
> >> +*value)
> >> {
> >> u32 reg_val;
> >> u64 reg_val64, min, max;
> >> + mutex_lock(&hwmon->hwmon_lock);
> >> +
> >> xe_hwmon_process_reg(hwmon, REG_PKG_RAPL_LIMIT, REG_READ,
> >> ®_val, 0, 0);
> >> /* Check if PL1 limit is disabled */
> >> if (!(reg_val & PKG_PWR_LIM_1_EN)) {
> >> *value = PL1_DISABLE;
> >> - return 0;
> >> + goto unlock;
> >> }
> >> reg_val = REG_FIELD_GET(PKG_PWR_LIM_1, reg_val); @@ -169,14
> >> +169,17 @@ static int xe_hwmon_power_max_read(struct xe_hwmon
> *hwmon,
> >> long *value)
> >> if (min && max)
> >> *value = clamp_t(u64, *value, min, max);
> >> -
> >> - return 0;
> >> +unlock:
> >> + mutex_unlock(&hwmon->hwmon_lock);
> >> }
> >> static int xe_hwmon_power_max_write(struct xe_hwmon *hwmon, long
> >> value)
> >> {
> >> + int ret = 0;
> >> u32 reg_val;
> >> + mutex_lock(&hwmon->hwmon_lock);
> >> +
> >> /* Disable PL1 limit and verify, as limit cannot be disabled on
> >> all platforms */
> >> if (value == PL1_DISABLE) {
> >> xe_hwmon_process_reg(hwmon, REG_PKG_RAPL_LIMIT, REG_RMW,
> >> ®_val, @@ -184,8 +187,10 @@ static int
> >> xe_hwmon_power_max_write(struct xe_hwmon *hwmon, long value)
> >> xe_hwmon_process_reg(hwmon, REG_PKG_RAPL_LIMIT, REG_READ,
> >> ®_val,
> >> PKG_PWR_LIM_1_EN, 0);
> >> - if (reg_val & PKG_PWR_LIM_1_EN)
> >> - return -EOPNOTSUPP;
> >> + if (reg_val & PKG_PWR_LIM_1_EN) {
> >> + ret = -EOPNOTSUPP;
> >> + goto unlock;
> >> + }
> >> }
> >> /* Computation in 64-bits to avoid overflow. Round to nearest.
> >> */ @@ -194,19 +199,18 @@ static int
> xe_hwmon_power_max_write(struct
> >> xe_hwmon *hwmon, long value)
> >> xe_hwmon_process_reg(hwmon, REG_PKG_RAPL_LIMIT, REG_RMW,
> >> ®_val,
> >> PKG_PWR_LIM_1_EN | PKG_PWR_LIM_1, reg_val);
> >> -
> >> - return 0;
> >> +unlock:
> >> + mutex_unlock(&hwmon->hwmon_lock);
> >> + return ret;
> >> }
> >> -static int xe_hwmon_power_rated_max_read(struct xe_hwmon *hwmon,
> >> long
> >> *value)
> >> +static void xe_hwmon_power_rated_max_read(struct xe_hwmon
> *hwmon,
> >> long *value)
> >> {
> >> u32 reg_val;
> >> xe_hwmon_process_reg(hwmon, REG_PKG_POWER_SKU, REG_READ,
> >> ®_val, 0, 0);
> >> reg_val = REG_FIELD_GET(PKG_TDP, reg_val);
> >> *value = mul_u64_u32_shr(reg_val, SF_POWER,
> >> hwmon->scl_shift_power);
> >> -
> >> - return 0;
> >> }
> >> /*
> >> @@ -235,10 +239,6 @@ xe_hwmon_energy_get(struct xe_hwmon
> *hwmon, long
> >> *energy)
> >> struct xe_hwmon_energy_info *ei = &hwmon->ei;
> >> u32 reg_val;
> >> - xe_device_mem_access_get(gt_to_xe(hwmon->gt));
> >> -
> >> - mutex_lock(&hwmon->hwmon_lock);
> >> -
> >> xe_hwmon_process_reg(hwmon, REG_PKG_ENERGY_STATUS,
> REG_READ,
> >> ®_val, 0, 0);
> >> @@ -251,10 +251,6 @@ xe_hwmon_energy_get(struct xe_hwmon
> *hwmon, long
> >> *energy)
> >> *energy = mul_u64_u32_shr(ei->accum_energy, SF_ENERGY,
> >> hwmon->scl_shift_energy);
> >> -
> >> - mutex_unlock(&hwmon->hwmon_lock);
> >> -
> >> - xe_device_mem_access_put(gt_to_xe(hwmon->gt));
> >> }
> >> static const struct hwmon_channel_info *hwmon_info[] = { @@ -284,6
> >> +280,38 @@ static int xe_hwmon_pcode_write_i1(struct xe_gt *gt, u32
> >> uval)
> >> uval);
> >> }
> >> +static int xe_hwmon_power_curr_crit_read(struct xe_hwmon *hwmon,
> >> +long
> >> *value, u32 scale_factor)
> >> +{
> >> + int ret;
> >> + u32 uval;
> >> +
> >> + mutex_lock(&hwmon->hwmon_lock);
> >> +
> >> + ret = xe_hwmon_pcode_read_i1(hwmon->gt, &uval);
> >> + if (ret)
> >> + goto unlock;
> >> +
> >> + *value =
> mul_u64_u32_shr(REG_FIELD_GET(POWER_SETUP_I1_DATA_MASK,
> >> uval),
> >> + scale_factor, POWER_SETUP_I1_SHIFT);
> >> +unlock:
> >> + mutex_unlock(&hwmon->hwmon_lock);
> >> + return ret;
> >> +}
> >> +
> >> +static int xe_hwmon_power_curr_crit_write(struct xe_hwmon *hwmon,
> >> long value, u32 scale_factor)
> >> +{
> >> + int ret;
> >> + u32 uval;
> >> +
> >> + mutex_lock(&hwmon->hwmon_lock);
> >> +
> >> + uval = DIV_ROUND_CLOSEST_ULL(value << POWER_SETUP_I1_SHIFT,
> >> scale_factor);
> >> + ret = xe_hwmon_pcode_write_i1(hwmon->gt, uval);
> >> +
> >> + mutex_unlock(&hwmon->hwmon_lock);
> >> + return ret;
> >> +}
> >> +
> >> static int xe_hwmon_get_voltage(struct xe_hwmon *hwmon, long
> >> *value)
> >> {
> >> u32 reg_val;
> >> @@ -317,23 +345,15 @@ xe_hwmon_power_is_visible(struct xe_hwmon
> >> *hwmon, u32 attr, int chan)
> >> static int
> >> xe_hwmon_power_read(struct xe_hwmon *hwmon, u32 attr, int chan,
> >> long
> >> *val)
> >> {
> >> - int ret;
> >> - u32 uval;
> >> -
> >> switch (attr) {
> >> case hwmon_power_max:
> >> - return xe_hwmon_power_max_read(hwmon, val);
> >> + xe_hwmon_power_max_read(hwmon, val);
> >> + return 0;
> >> case hwmon_power_rated_max:
> >> - return xe_hwmon_power_rated_max_read(hwmon, val);
> >> - case hwmon_power_crit:
> >> - ret = xe_hwmon_pcode_read_i1(hwmon->gt, &uval);
> >> - if (ret)
> >> - return ret;
> >> - if (!(uval & POWER_SETUP_I1_WATTS))
> >> - return -ENODEV;
> >> - *val =
> >> mul_u64_u32_shr(REG_FIELD_GET(POWER_SETUP_I1_DATA_MASK, uval),
> >> - SF_POWER, POWER_SETUP_I1_SHIFT);
> >> + xe_hwmon_power_rated_max_read(hwmon, val);
> >> return 0;
> >> + case hwmon_power_crit:
> >> + return xe_hwmon_power_curr_crit_read(hwmon, val, SF_POWER);
> >> default:
> >> return -EOPNOTSUPP;
> >> }
> >> @@ -342,14 +362,11 @@ xe_hwmon_power_read(struct xe_hwmon
> *hwmon, u32
> >> attr, int chan, long *val)
> >> static int
> >> xe_hwmon_power_write(struct xe_hwmon *hwmon, u32 attr, int chan,
> >> long val)
> >> {
> >> - u32 uval;
> >> -
> >> switch (attr) {
> >> case hwmon_power_max:
> >> return xe_hwmon_power_max_write(hwmon, val);
> >> case hwmon_power_crit:
> >> - uval = DIV_ROUND_CLOSEST_ULL(val << POWER_SETUP_I1_SHIFT,
> >> SF_POWER);
> >> - return xe_hwmon_pcode_write_i1(hwmon->gt, uval);
> >> + return xe_hwmon_power_curr_crit_write(hwmon, val, SF_POWER);
> >> default:
> >> return -EOPNOTSUPP;
> >> }
> >> @@ -372,19 +389,9 @@ xe_hwmon_curr_is_visible(const struct
> xe_hwmon
> >> *hwmon, u32 attr)
> >> static int
> >> xe_hwmon_curr_read(struct xe_hwmon *hwmon, u32 attr, long *val)
> >> {
> >> - int ret;
> >> - u32 uval;
> >> -
> >> switch (attr) {
> >> case hwmon_curr_crit:
> >> - ret = xe_hwmon_pcode_read_i1(hwmon->gt, &uval);
> >> - if (ret)
> >> - return ret;
> >> - if (uval & POWER_SETUP_I1_WATTS)
> >> - return -ENODEV;
> >> - *val =
> >> mul_u64_u32_shr(REG_FIELD_GET(POWER_SETUP_I1_DATA_MASK, uval),
> >> - SF_CURR, POWER_SETUP_I1_SHIFT);
> >> - return 0;
> >> + return xe_hwmon_power_curr_crit_read(hwmon, val, SF_CURR);
> >> default:
> >> return -EOPNOTSUPP;
> >> }
> >> @@ -393,12 +400,9 @@ xe_hwmon_curr_read(struct xe_hwmon
> *hwmon, u32
> >> attr, long *val)
> >> static int
> >> xe_hwmon_curr_write(struct xe_hwmon *hwmon, u32 attr, long val)
> >> {
> >> - u32 uval;
> >> -
> >> switch (attr) {
> >> case hwmon_curr_crit:
> >> - uval = DIV_ROUND_CLOSEST_ULL(val << POWER_SETUP_I1_SHIFT,
> >> SF_CURR);
> >> - return xe_hwmon_pcode_write_i1(hwmon->gt, uval);
> >> + return xe_hwmon_power_curr_crit_write(hwmon, val, SF_CURR);
> >> default:
> >> return -EOPNOTSUPP;
> >> }
> >> @@ -420,8 +424,6 @@ xe_hwmon_in_read(struct xe_hwmon *hwmon,
> u32
> >> attr, long *val)
> >> {
> >> int ret;
> >> - xe_device_mem_access_get(gt_to_xe(hwmon->gt));
> >> -
> >> switch (attr) {
> >> case hwmon_in_input:
> >> ret = xe_hwmon_get_voltage(hwmon, val); @@ -430,8 +432,6 @@
> >> xe_hwmon_in_read(struct xe_hwmon *hwmon, u32 attr, long *val)
> >> ret = -EOPNOTSUPP;
> >> }
> >> - xe_device_mem_access_put(gt_to_xe(hwmon->gt));
> >> -
> >> return ret;
> >> }
> >> @@ -565,14 +565,13 @@ xe_hwmon_get_preregistration_info(struct
> >> xe_device *xe)
> >> struct xe_hwmon *hwmon = xe->hwmon;
> >> long energy;
> >> u32 val_sku_unit = 0;
> >> - int ret;
> >> - ret = xe_hwmon_process_reg(hwmon, REG_PKG_POWER_SKU_UNIT,
> >> REG_READ, &val_sku_unit, 0, 0);
> >> /*
> >> * The contents of register PKG_POWER_SKU_UNIT do not change,
> >> * so read it once and store the shift values.
> >> */
> >> - if (!ret) {
> >> + if (xe_hwmon_get_reg(hwmon, REG_PKG_POWER_SKU_UNIT)) {
> >> + xe_hwmon_process_reg(hwmon, REG_PKG_POWER_SKU_UNIT,
> >> +REG_READ,
> >> &val_sku_unit, 0, 0);
> >> hwmon->scl_shift_power = REG_FIELD_GET(PKG_PWR_UNIT,
> >> val_sku_unit);
> >> hwmon->scl_shift_energy = REG_FIELD_GET(PKG_ENERGY_UNIT,
> >> val_sku_unit);
> >> }
