Re: [PATCH v3 1/3] drm/xe/soc_remapper: Initialize SoC remapper during Xe probe

["Nilawar, Badal" <badal.nilawar@intel.com>]

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On 03-12-2025 22:36, Umesh Nerlige Ramappa wrote:
> On Tue, Dec 02, 2025 at 04:48:02PM -0800, Umesh Nerlige Ramappa wrote:
>> SoC remapper is used to map different HW functions in the SoC to their
>> respective drivers. Initialize SoC remapper during driver load.
>>
>> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>> ---
>> v2: (Ashutosh/Lucas)
>> - s/remapper/soc_remapper/
>> - return status from init during probe
>> - reorder patches 1 and 2 from earlier series
>> - fix copyright year
>>
>> v3: (Michal, Badal)
>> - Kernel doc fixes
>> - Alphabetical order for headers/objects
>> - Add has_soc_remapper
>> - Drop unnecessary headers
>> ---
>> drivers/gpu/drm/xe/Makefile          |  1 +
>> drivers/gpu/drm/xe/xe_device.c       |  5 +++++
>> drivers/gpu/drm/xe/xe_device_types.h |  8 ++++++++
>> drivers/gpu/drm/xe/xe_pci.c          |  2 ++
>> drivers/gpu/drm/xe/xe_pci_types.h    |  2 ++
>> drivers/gpu/drm/xe/xe_soc_remapper.c | 24 ++++++++++++++++++++++++
>> drivers/gpu/drm/xe/xe_soc_remapper.h | 13 +++++++++++++
>> 7 files changed, 55 insertions(+)
>> create mode 100644 drivers/gpu/drm/xe/xe_soc_remapper.c
>> create mode 100644 drivers/gpu/drm/xe/xe_soc_remapper.h
>>
>> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
>> index 0eadfeda67d9..06c3987afd4c 100644
>> --- a/drivers/gpu/drm/xe/Makefile
>> +++ b/drivers/gpu/drm/xe/Makefile
>> @@ -115,6 +115,7 @@ xe-y += xe_bb.o \
>>     xe_sa.o \
>>     xe_sched_job.o \
>>     xe_shrinker.o \
>> +    xe_soc_remapper.o \
>>     xe_step.o \
>>     xe_survivability_mode.o \
>>     xe_sync.o \
>> diff --git a/drivers/gpu/drm/xe/xe_device.c 
>> b/drivers/gpu/drm/xe/xe_device.c
>> index 92f883dd8877..b54fc5852fef 100644
>> --- a/drivers/gpu/drm/xe/xe_device.c
>> +++ b/drivers/gpu/drm/xe/xe_device.c
>> @@ -61,6 +61,7 @@
>> #include "xe_pxp.h"
>> #include "xe_query.h"
>> #include "xe_shrinker.h"
>> +#include "xe_soc_remapper.h"
>> #include "xe_survivability_mode.h"
>> #include "xe_sriov.h"
>> #include "xe_tile.h"
>> @@ -906,6 +907,10 @@ int xe_device_probe(struct xe_device *xe)
>>
>>     xe_nvm_init(xe);
>>
>> +    err = xe_soc_remapper_init(xe);
>> +    if (err)
>> +        return err;
>> +
>>     err = xe_heci_gsc_init(xe);
>>     if (err)
>>         return err;
>> diff --git a/drivers/gpu/drm/xe/xe_device_types.h 
>> b/drivers/gpu/drm/xe/xe_device_types.h
>> index 9a9a8eb84a78..450fe703a3b9 100644
>> --- a/drivers/gpu/drm/xe/xe_device_types.h
>> +++ b/drivers/gpu/drm/xe/xe_device_types.h
>> @@ -315,6 +315,8 @@ struct xe_device {
>>         u8 has_pxp:1;
>>         /** @info.has_range_tlb_inval: Has range based TLB 
>> invalidations */
>>         u8 has_range_tlb_inval:1;
>> +        /** @info.has_soc_remapper: Has SoC remapper support */
>> +        u8 has_soc_remapper:1;
>>         /** @info.has_sriov: Supports SR-IOV */
>>         u8 has_sriov:1;
>>         /** @info.has_usm: Device has unified shared memory support */
>> @@ -555,6 +557,12 @@ struct xe_device {
>>         struct mutex lock;
>>     } pmt;
>>
>> +    /** @soc_remapper: SoC remapper object */
>> +    struct {
>> +        /** @soc_remapper.lock: Serialize access to SoC Remapper's 
>> index registers */
>> +        spinlock_t lock;
>> +    } soc_remapper;
>> +
>>     /**
>>      * @pm_callback_task: Track the active task that is running in 
>> either
>>      * the runtime_suspend or runtime_resume callbacks.
>> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
>> index 75e3588242c7..ec0fed691fa0 100644
>> --- a/drivers/gpu/drm/xe/xe_pci.c
>> +++ b/drivers/gpu/drm/xe/xe_pci.c
>> @@ -413,6 +413,7 @@ static const struct xe_device_desc cri_desc = {
>>     .has_flat_ccs = false,
>>     .has_mbx_power_limits = true,
>>     .has_mert = true,
>> +    .has_soc_remapper = true,
>
> Needs to be enabled for BMG also, hence the BAT failure.

We should use has_soc_remapper not just for protecting spinlock 
initialization, but also for guarding soc remapper accesses.

Since there are two soc remappers—SC and Telemetry—we could update 
has_soc_remapper to use 2 bits (u8 has_soc_remapper:2), and set only the 
relevant bits in the platform descriptor. For example:

static const struct xe_device_desc bmg_desc = {
     .has_soc_remapper = SOC_REMAP_TELEM

static const struct xe_device_desc cri_desc = {
     .has_soc_remapper = SOC_REMAP_TELEM | SOC_REMAP_SC

If we prefer a true/false approach, we should use two separate flags: 
has_soc_telem_remapper and has_soc_sc_remapper.

Thanks,
Badal

> Umesh

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