Re: [PATCH v4 6/6] hwmon: (peci/dimmtemp) Add support for Granite Rapids (GNR)

[Winiarska, Iwona]

On Fri, 2026-10-30 at 12:56 -0700, Guenter Roeck wrote:
> On Mon, Oct 19, 2026 at 04:45:02AM -0700, Changhuang Liang wrote:
> > Add support for Granite Rapids (GNR) platform in PECI DIMM temperature
> > monitoring driver.
> > 
> > The GNR platform has different DIMM topology from previous generations,
> > with 12 channel ranks (CHAN_RANK_MAX_ON_GNR) and 2 DIMM indexes per
> > channel. Define these new constants and update CHAN_RANK_MAX to use
> > the GNR value since it represents the maximum across all supported
> > platforms.
> > 
> > Since the current peci core does not support domains, accessing GNR's
> > DIMM_TEMP_MAX and DIMM_TEMP_CRIT via PECI commands will be rejected
> > and return completion code 0x90 (invalid request). To handle this, the
> > read_thresholds callback is not defined for GNR, and the visibility
> > logic is updated to skip exposing the max and crit temperature
> > attributes.
> > 
> > The minimum PECI revision required for GNR is 0x42.
> > 
> > Signed-off-by: Changhuang Liang <changhuang.liang@xxxxxxxxxxxxxxxx>
> > Reviewed-by: Iwona Winiarska <iwona.winiarska@xxxxxxxxx>
> 
> Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Hi Guenter!

Could you please take the hwmon changes through your tree?

Thanks
-Iwona

> 
> > ---
> >  drivers/hwmon/peci/dimmtemp.c | 33 +++++++++++++++++++++++++++++----
> >  1 file changed, 29 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/hwmon/peci/dimmtemp.c b/drivers/hwmon/peci/dimmtemp.c
> > index bd3e8715dfec..791a8e866081 100644
> > --- a/drivers/hwmon/peci/dimmtemp.c
> > +++ b/drivers/hwmon/peci/dimmtemp.c
> > @@ -34,8 +34,10 @@
> >  #define DIMM_IDX_MAX_ON_SPR	2
> >  #define CHAN_RANK_MAX_ON_EMR	8
> >  #define DIMM_IDX_MAX_ON_EMR	2
> > +#define CHAN_RANK_MAX_ON_GNR	12
> > +#define DIMM_IDX_MAX_ON_GNR	2
> >  
> > -#define CHAN_RANK_MAX		CHAN_RANK_MAX_ON_HSX
> > +#define CHAN_RANK_MAX		CHAN_RANK_MAX_ON_GNR
> >  #define DIMM_IDX_MAX		DIMM_IDX_MAX_ON_HSX
> >  #define DIMM_NUMS_MAX		(CHAN_RANK_MAX * DIMM_IDX_MAX)
> >  
> > @@ -198,10 +200,18 @@ static umode_t dimmtemp_is_visible(const void *data,
> > enum hwmon_sensor_types typ
> >  {
> >  	const struct peci_dimmtemp *priv = data;
> >  
> > -	if (test_bit(channel, priv->dimm_mask))
> > -		return 0444;
> > +	if (!test_bit(channel, priv->dimm_mask))
> > +		return 0;
> >  
> > -	return 0;
> > +	/*
> > +	 * Some platforms do not provide the DIMM temperature thresholds
> > over
> > +	 * PECI - do not expose the corresponding attributes there.
> > +	 */
> > +	if ((attr == hwmon_temp_max || attr == hwmon_temp_crit) &&
> > +	    !priv->gen_info->read_thresholds)
> > +		return 0;
> > +
> > +	return 0444;
> >  }
> >  
> >  static const struct hwmon_ops peci_dimmtemp_ops = {
> > @@ -626,6 +636,17 @@ static const struct dimm_info dimm_emr = {
> >  	.read_thresholds = &read_thresholds_emr,
> >  };
> >  
> > +static const struct dimm_info dimm_gnr = {
> > +	.chan_rank_max	= CHAN_RANK_MAX_ON_GNR,
> > +	.dimm_idx_max	= DIMM_IDX_MAX_ON_GNR,
> > +	.min_peci_revision = 0x42,
> > +	/*
> > +	 * Reading DIMM_TEMP_MAX/DIMM_TEMP_CRIT over PECI is answered with
> > +	 * completion code 0x90 (invalid request) on Granite Rapids, so the
> > +	 * threshold attributes are not exposed on this platform.
> > +	 */
> > +};
> > +
> >  static const struct auxiliary_device_id peci_dimmtemp_ids[] = {
> >  	{
> >  		.name = "peci_cpu.dimmtemp.hsx",
> > @@ -659,6 +680,10 @@ static const struct auxiliary_device_id
> > peci_dimmtemp_ids[] = {
> >  		.name = "peci_cpu.dimmtemp.emr",
> >  		.driver_data = (kernel_ulong_t)&dimm_emr,
> >  	},
> > +	{
> > +		.name = "peci_cpu.dimmtemp.gnr",
> > +		.driver_data = (kernel_ulong_t)&dimm_gnr,
> > +	},
> >  	{ }
> >  };
> >  MODULE_DEVICE_TABLE(auxiliary, peci_dimmtemp_ids);