From: Matthew Brost <matthew.brost@xxxxxxxxx>
With the introduction of non-blocking CTBs more than one CTB can be in
flight at a time. Increasing the size of the CTBs should reduce how
often software hits the case where no space is available in the CTB
buffer.
Cc: John Harrison <john.c.harrison@xxxxxxxxx>
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 50 +++++++++++++++--------
1 file changed, 32 insertions(+), 18 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 4d8a4c6afd71..31c512e7ecc2 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
@@ -14,6 +14,10 @@
#define CT_DEBUG_DRIVER(...) do { } while (0)
#endif
+#define CTB_DESC_SIZE (PAGE_SIZE / 2)
+#define CTB_H2G_BUFFER_SIZE (PAGE_SIZE)
+#define CTB_G2H_BUFFER_SIZE (CTB_H2G_BUFFER_SIZE * 2)
+
#define MAX_RETRY 0x1000000
struct ct_request {
@@ -143,30 +147,35 @@ static int ctch_init(struct intel_guc *guc,
GEM_BUG_ON(ctch->vma);
- /* We allocate 1 page to hold both descriptors and both buffers.
+ /* We allocate 3 pages to hold both descriptors and both buffers.
* ___________.....................
* |desc (SEND)| :
- * |___________| PAGE/4
+ * |___________| PAGE/2
* :___________....................:
* |desc (RECV)| :
- * |___________| PAGE/4
+ * |___________| PAGE/2
* :_______________________________:
* |cmds (SEND) |
- * | PAGE/4
+ * | PAGE
* |_______________________________|
* |cmds (RECV) |
- * | PAGE/4
+ * | PAGE * 2
* |_______________________________|
*
* 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.
+ * have more than 1 in flight at any time, unless we are using the GuC
+ * submission. In that case each request requires a minimum 8 bytes
+ * which gives us a maximum 512 queue'd requests. Hopefully this enough
+ * space to avoid backpressure on the driver. We also double the size of
+ * the receive buffer (relative to the send) to ensure a g2h response
+ * CTB has a landing spot.
*/
/* allocate vma */
- vma = intel_guc_allocate_vma(guc, PAGE_SIZE);
+ vma = intel_guc_allocate_vma(guc, CTB_DESC_SIZE *
+ ARRAY_SIZE(ctch->ctbs) +
+ CTB_H2G_BUFFER_SIZE +
+ CTB_G2H_BUFFER_SIZE);
if (IS_ERR(vma)) {
err = PTR_ERR(vma);
goto err_out;
@@ -185,8 +194,9 @@ static int ctch_init(struct intel_guc *guc,
/* store pointers to desc and cmds */
for (i = 0; i < ARRAY_SIZE(ctch->ctbs); i++) {
GEM_BUG_ON((i != CTB_SEND) && (i != CTB_RECV));
- ctch->ctbs[i].desc = blob + PAGE_SIZE/4 * i;
- ctch->ctbs[i].cmds = blob + PAGE_SIZE/4 * i + PAGE_SIZE/2;
+ ctch->ctbs[i].desc = blob + CTB_DESC_SIZE * i;
+ ctch->ctbs[i].cmds = blob + CTB_H2G_BUFFER_SIZE * i +
+ CTB_DESC_SIZE * ARRAY_SIZE(ctch->ctbs);
}
return 0;
@@ -210,7 +220,7 @@ static void ctch_fini(struct intel_guc *guc,
static int ctch_enable(struct intel_guc *guc,
struct intel_guc_ct_channel *ctch)
{
- u32 base;
+ u32 base, size;
int err;
int i;
@@ -226,9 +236,12 @@ static int ctch_enable(struct intel_guc *guc,
*/
for (i = 0; i < ARRAY_SIZE(ctch->ctbs); i++) {
GEM_BUG_ON((i != CTB_SEND) && (i != CTB_RECV));
+ size = (i == CTB_SEND) ? CTB_H2G_BUFFER_SIZE :
+ CTB_G2H_BUFFER_SIZE;
guc_ct_buffer_desc_init(&ctch->ctbs[i],
- base + PAGE_SIZE/4 * i + PAGE_SIZE/2,
- PAGE_SIZE/4,
+ base + CTB_H2G_BUFFER_SIZE * i +
+ CTB_DESC_SIZE * ARRAY_SIZE(ctch->ctbs),
+ size,
ctch->owner);
}
@@ -236,13 +249,13 @@ static int ctch_enable(struct intel_guc *guc,
* descriptors are in first half of the blob
*/
err = guc_action_register_ct_buffer(guc,
- base + PAGE_SIZE/4 * CTB_RECV,
+ base + CTB_DESC_SIZE * CTB_RECV,
INTEL_GUC_CT_BUFFER_TYPE_RECV);
if (unlikely(err))
goto err_out;
err = guc_action_register_ct_buffer(guc,
- base + PAGE_SIZE/4 * CTB_SEND,
+ base + CTB_DESC_SIZE * CTB_SEND,
INTEL_GUC_CT_BUFFER_TYPE_SEND);
if (unlikely(err))
goto err_deregister;
@@ -635,7 +648,8 @@ static int ctb_read(struct intel_guc_ct_buffer *ctb, u32 *data)
/* beware of buffer wrap case */
if (unlikely(available < 0))
available += size;
- CT_DEBUG_DRIVER("CT: available %d (%u:%u)\n", available, head, tail);
+ CT_DEBUG_DRIVER("CT: available %d (%u:%u:%d)\n", available, head, tail,
+ size);
GEM_BUG_ON(available < 0);
data[0] = cmds[head];
--
2.21.0.5.gaeb582a983
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