[PATCH v5 1/1] drm/xe: Expose number of dss per group and helpers
Dong, Zhanjun
zhanjun.dong at intel.com
Wed Jan 31 15:47:32 UTC 2024
On 2024-01-30 7:09 p.m., Matt Roper wrote:
> On Tue, Jan 30, 2024 at 01:22:08PM -0800, Zhanjun Dong wrote:
>> Expose helper for dss per group. This is a precursor patch to allow
>> for easier iteration through MCR registers and other per-DSS uses.
>>
>> Signed-off-by: Zhanjun Dong <zhanjun.dong at intel.com>
>> ---
>> drivers/gpu/drm/xe/xe_gt_mcr.c | 40 ++++++++++++++++++++++++++++-
>> drivers/gpu/drm/xe/xe_gt_mcr.h | 17 ++++++++++++
>> drivers/gpu/drm/xe/xe_gt_topology.c | 3 ---
>> drivers/gpu/drm/xe/xe_gt_types.h | 2 ++
>> 4 files changed, 58 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
>> index 77925b35cf8d..ad2e42dc2218 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_mcr.c
>> +++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
>> @@ -291,11 +291,16 @@ static void init_steering_mslice(struct xe_gt *gt)
>> gt->steering[LNCF].instance_target = 0; /* unused */
>> }
>>
>> +int xe_gt_mcr_get_dss_per_group(struct xe_gt *gt)
>> +{
>> + return gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
>> +}
>> +
>> static void init_steering_dss(struct xe_gt *gt)
>> {
>> unsigned int dss = min(xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0),
>> xe_dss_mask_group_ffs(gt->fuse_topo.c_dss_mask, 0, 0));
>> - unsigned int dss_per_grp = gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
>> + unsigned int dss_per_grp = xe_gt_mcr_get_dss_per_group(gt);
>>
>> gt->steering[DSS].group_target = dss / dss_per_grp;
>> gt->steering[DSS].instance_target = dss % dss_per_grp;
>
> To avoid duplicating the logic, we could just replace these lines with a
> call to your new xe_gt_mcr_get_dss_steering() function as well. Then we
> don't even need the dss_per_grp local variable.
There are pointer type mismatch issue, both
gt->steering[DSS].group_target and gt->steering[DSS].instance_target are
u16, while xe_gt_mcr_get_dss_steering take uint*, which called by the
macro and get the pointer from macro. I would prefer leave int type as
macro argument type as it is easy and safe way to avoid write 4/8 bytes
to 2 bytes data.
Let's leave the part as is to avoid u16* vs uint* type issue.
>
>> @@ -683,3 +688,36 @@ void xe_gt_mcr_steering_dump(struct xe_gt *gt, struct drm_printer *p)
>> }
>> }
>> }
>> +
>> +/**
>> + * xe_gt_mcr_get_dss_steering - returns the group/instance steering for a DSS
>> + * @gt: GT structure
>> + * @dss: DSS ID to obtain steering for
>> + * @group: pointer to storage for steering group ID
>> + * @instance: pointer to storage for steering instance ID
>> + *
>> + * Returns the steering IDs (via the @group and @instance parameters) that
>> + * correspond to a specific DSS ID.
>> + */
>> +void xe_gt_mcr_get_dss_steering(struct xe_gt *gt, unsigned int dss, unsigned int *group,
>> + unsigned int *instance)
>> +{
>> + int dss_per_grp = xe_gt_mcr_get_dss_per_group(gt);
>> +
>> + *group = dss / dss_per_grp;
>> + *instance = dss % dss_per_grp;
>> +}
>> +
>> +bool xe_gt_mcr_dss_has_subslice(struct xe_gt *gt, int slice, int subslice)
>
> "dss" and "subslice" are basically two terms for the same thing so this
> name is a bit redundant. Something like "xe_gt_mcr_has_dss" would
> probably be fine?
>
> Although this should probably be in xe_gt_topology rather than xe_gt_mcr
> since it deals more with the hardware topology than with steering. So
> moving it over to that file, the name would become
> "xe_gt_topology_has_dss."
Moved to xe_gt_topology is fine, because the function need dss per group
to do calculation, then it requires xe_gt_mcr_get_dss_per_group exposed.
>
>> +{
>> + int dss_per_grp = xe_gt_mcr_get_dss_per_group(gt);
>> + int index = slice * dss_per_grp + subslice;
>> +
>> + if (index >= XE_MAX_DSS_FUSE_BITS) {
>> + xe_gt_dbg(gt, "DSS id out of range: slice:%d subslice:%d\n", slice, subslice);
>> + return false;
>> + }
>> +
>> + return test_bit(index, gt->fuse_topo.g_dss_mask) ||
>> + test_bit(index, gt->fuse_topo.c_dss_mask);
>> +}
>> diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.h b/drivers/gpu/drm/xe/xe_gt_mcr.h
>> index 27ca1bc880a0..356f21978eb8 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_mcr.h
>> +++ b/drivers/gpu/drm/xe/xe_gt_mcr.h
>> @@ -7,6 +7,7 @@
>> #define _XE_GT_MCR_H_
>>
>> #include "regs/xe_reg_defs.h"
>> +#include "xe_gt_types.h"
>>
>> struct drm_printer;
>> struct xe_gt;
>> @@ -25,5 +26,21 @@ void xe_gt_mcr_multicast_write(struct xe_gt *gt, struct xe_reg_mcr mcr_reg,
>> u32 value);
>>
>> void xe_gt_mcr_steering_dump(struct xe_gt *gt, struct drm_printer *p);
>> +int xe_gt_mcr_get_dss_per_group(struct xe_gt *gt);
>
> It doesn't look like you actually use this outside of xe_gt_mcr.c
> anymore so we probably don't need to export it. It can remain a static
> function for now.
Same to above, move xe_gt_mcr_has_dss to xe_gt_topology.c conflicts with
this static prototype definition.
>
>> +void xe_gt_mcr_get_dss_steering(struct xe_gt *gt, unsigned int dss, unsigned int *group,
>> + unsigned int *instance);
>> +bool xe_gt_mcr_dss_has_subslice(struct xe_gt *gt, int slice, int subslice);
>> +
>> +#define _HAS_DSS(gt__, group__, instance__) xe_gt_mcr_dss_has_subslice(gt__, group__, instance__)
>
> I don't think we need this macro which is just a pure alias for the real
> function.
Sure, will take it off.
>
>> +
>> +/*
>> + * Loop over each subslice/DSS and determine the group and instance IDs that
>> + * should be used to steer MCR accesses toward this DSS.
>> + */
>> +#define for_each_dss_steering(dss_, gt_, group_, instance_) \
>> + for (dss_ = 0, xe_gt_mcr_get_dss_steering(gt_, 0, &(group_), &(instance_)); \
>> + dss_ < XE_MAX_DSS_FUSE_BITS; \
>> + dss_++, xe_gt_mcr_get_dss_steering(gt_, dss_, &(group_), &(instance_))) \
>> + for_each_if(_HAS_DSS(gt_, (group_), (instance_)))
>
> We could also probably implement this more efficiently if we had a
> topology helper like this (untested):
>
> int xe_gt_topology_get_next_dss(struct xe_gt *gt, int from) {
> xe_dss_mask_t all_dss;
> unsigned long next;
>
> bitmap_or(all_dss,
> gt->fuse_topo.g_dss_mask,
> gt->fuse_topo.c_dss_mask,
> XE_MAX_DSS_FUSE_BITS);
>
> next = find_next_bit(all_dss, XE_MAX_DSS_FUSE_BITS, from);
> if (next == XE_MAX_DSS_FUSE_BITS)
> return -1;
>
> return next;
> }
>
> Then you could write these loops as something like:
>
> #define for_each_dss_steering(dss_, gt_, group_, instance_) \
> for (dss_ = xe_gt_topology_get_next_dss(gt, 0); \
> dss_ >= 0; \
> dss_ = xe_gt_topology_get_next_dss(gt, dss_ + 1)) \
>
The macro above actually not set group_ and instance_, while the macro
for_each_dss_steering designed is to iterate all dss id, call a code
block, with group_ and instance_ already set. In my review comments to
Jose's patch, I have similar optimization, but revert back because of
the same group_ and instance_ not set reason.
> That also avoids leaking the XE_MAX_DSS_FUSE_BITS internal detail
> outside the topology files.
>
>>
>> #endif /* _XE_GT_MCR_H_ */
>> diff --git a/drivers/gpu/drm/xe/xe_gt_topology.c b/drivers/gpu/drm/xe/xe_gt_topology.c
>> index a8d7f272c30a..e973eeaac7f1 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_topology.c
>> +++ b/drivers/gpu/drm/xe/xe_gt_topology.c
>> @@ -11,9 +11,6 @@
>> #include "xe_gt.h"
>> #include "xe_mmio.h"
>>
>> -#define XE_MAX_DSS_FUSE_BITS (32 * XE_MAX_DSS_FUSE_REGS)
>> -#define XE_MAX_EU_FUSE_BITS (32 * XE_MAX_EU_FUSE_REGS)
>> -
>> static void
>> load_dss_mask(struct xe_gt *gt, xe_dss_mask_t mask, int numregs, ...)
>> {
>> diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
>> index 70c615dd1498..b926606edb38 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_types.h
>> +++ b/drivers/gpu/drm/xe/xe_gt_types.h
>> @@ -25,7 +25,9 @@ enum xe_gt_type {
>> };
>>
>> #define XE_MAX_DSS_FUSE_REGS 3
>> +#define XE_MAX_DSS_FUSE_BITS (32 * XE_MAX_DSS_FUSE_REGS)
>
> Based on the suggestions above, I don't think moving these will actually
> be necessary.
This bind with for_each_dss_steering macro define.
>
>
> Matt
>
>> #define XE_MAX_EU_FUSE_REGS 1
>> +#define XE_MAX_EU_FUSE_BITS (32 * XE_MAX_EU_FUSE_REGS)
>>
>> typedef unsigned long xe_dss_mask_t[BITS_TO_LONGS(32 * XE_MAX_DSS_FUSE_REGS)];
>> typedef unsigned long xe_eu_mask_t[BITS_TO_LONGS(32 * XE_MAX_EU_FUSE_REGS)];
>> --
>> 2.34.1
>>
>
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