On Thu, May 06, 2021 at 12:13:28PM -0700, Matthew Brost wrote:
> From: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
>
> Future GuC will require CTB buffers sizes to be multiple of 4K.
> Make these changes now as this shouldn't impact us too much.
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: John Harrison <john.c.harrison@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 60 ++++++++++++-----------
> 1 file changed, 32 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index c54a29176862..c87a0a8bef26 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -38,6 +38,32 @@ static inline struct drm_device *ct_to_drm(struct intel_guc_ct *ct)
> #define CT_PROBE_ERROR(_ct, _fmt, ...) \
> i915_probe_error(ct_to_i915(ct), "CT: " _fmt, ##__VA_ARGS__);
>
> +/**
> + * DOC: CTB Blob
> + *
> + * We allocate single blob to hold both CTB descriptors and buffers:
> + *
> + * +--------+-----------------------------------------------+------+
> + * | offset | contents | size |
> + * +========+===============================================+======+
> + * | 0x0000 | H2G `CTB Descriptor`_ (send) | |
> + * +--------+-----------------------------------------------+ 4K |
> + * | 0x0800 | G2H `CTB Descriptor`_ (recv) | |
> + * +--------+-----------------------------------------------+------+
> + * | 0x1000 | H2G `CT Buffer`_ (send) | n*4K |
> + * | | | |
> + * +--------+-----------------------------------------------+------+
> + * | 0x1000 | G2H `CT Buffer`_ (recv) | m*4K |
> + * | + n*4K | | |
> + * +--------+-----------------------------------------------+------+
> + *
> + * Size of each `CT Buffer`_ must be multiple of 4K.
> + * As we don't expect too many messages, for now use minimum sizes.
> + */
> +#define CTB_DESC_SIZE ALIGN(sizeof(struct guc_ct_buffer_desc), SZ_2K)
> +#define CTB_H2G_BUFFER_SIZE (SZ_4K)
> +#define CTB_G2H_BUFFER_SIZE (SZ_4K)
> +
> struct ct_request {
> struct list_head link;
> u32 fence;
> @@ -175,29 +201,7 @@ int intel_guc_ct_init(struct intel_guc_ct *ct)
>
> GEM_BUG_ON(ct->vma);
>
> - /* We allocate 1 page to hold both descriptors and both buffers.
> - * ___________.....................
> - * |desc (SEND)| :
> - * |___________| PAGE/4
> - * :___________....................:
> - * |desc (RECV)| :
> - * |___________| PAGE/4
> - * :_______________________________:
> - * |cmds (SEND) |
> - * | PAGE/4
> - * |_______________________________|
> - * |cmds (RECV) |
> - * | PAGE/4
> - * |_______________________________|
> - *
> - * Each message can use a maximum of 32 dwords and we don't expect to
> - * have more than 1 in flight at any time, so we have enough space.
> - * Some logic further ahead will rely on the fact that there is only 1
> - * page and that it is always mapped, so if the size is changed the
> - * other code will need updating as well.
> - */
> -
> - blob_size = PAGE_SIZE;
> + blob_size = 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE + CTB_G2H_BUFFER_SIZE;
> err = intel_guc_allocate_and_map_vma(guc, blob_size, &ct->vma, &blob);
> if (unlikely(err)) {
> CT_PROBE_ERROR(ct, "Failed to allocate %u for CTB data (%pe)\n",
> @@ -209,17 +213,17 @@ int intel_guc_ct_init(struct intel_guc_ct *ct)
>
> /* store pointers to desc and cmds for send ctb */
> desc = blob;
> - cmds = blob + PAGE_SIZE / 2;
> - cmds_size = PAGE_SIZE / 4;
> + cmds = blob + 2 * CTB_DESC_SIZE;
2 is a magic number here. Think it would be more clear with
CTB_NUMBER_DESC define here.
Michal what do you think? We can fix this in the next post of this with
your blessing.
With that nit:
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> + cmds_size = CTB_H2G_BUFFER_SIZE;
> CT_DEBUG(ct, "%s desc %#lx cmds %#lx size %u\n", "send",
> ptrdiff(desc, blob), ptrdiff(cmds, blob), cmds_size);
>
> guc_ct_buffer_init(&ct->ctbs.send, desc, cmds, cmds_size);
>
> /* store pointers to desc and cmds for recv ctb */
> - desc = blob + PAGE_SIZE / 4;
> - cmds = blob + PAGE_SIZE / 4 + PAGE_SIZE / 2;
> - cmds_size = PAGE_SIZE / 4;
> + desc = blob + CTB_DESC_SIZE;
> + cmds = blob + 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE;
> + cmds_size = CTB_G2H_BUFFER_SIZE;
> CT_DEBUG(ct, "%s desc %#lx cmds %#lx size %u\n", "recv",
> ptrdiff(desc, blob), ptrdiff(cmds, blob), cmds_size);
>
> --
> 2.28.0
>
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