Commit c26e289f authored by Matthew Brost's avatar Matthew Brost Committed by John Harrison
Browse files

drm/i915/guc: Increase size of CTB buffers 



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@intel.com>
Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarMichal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708162055.129996-4-matthew.brost@intel.com
parent dd9c0f3c

drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c

+8 −3
Original line number Diff line number Diff line
@@ -58,11 +58,16 @@ static inline struct drm_device *ct_to_drm(struct intel_guc_ct *ct) 
 *      +--------+-----------------------------------------------+------+

 *

 * Size of each `CT Buffer`_ must be multiple of 4K.

 * As we don't expect too many messages, for now use minimum sizes.

 * We don't expect too many messages in flight at any time, unless we are

 * using the GuC submission. In that case each request requires a minimum

 * 2 dwords which gives us a maximum 256 queue'd requests. Hopefully this

 * enough space to avoid backpressure on the driver. We increase the size

 * of the receive buffer (relative to the send) to ensure a G2H response

 * CTB has a landing spot.

 */

#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)

#define CTB_G2H_BUFFER_SIZE	(4 * CTB_H2G_BUFFER_SIZE)



struct ct_request {

	struct list_head link;
@@ -643,7 +648,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) 
	/* beware of buffer wrap case */

	if (unlikely(available < 0))

		available += size;

	CT_DEBUG(ct, "available %d (%u:%u)\n", available, head, tail);

	CT_DEBUG(ct, "available %d (%u:%u:%u)\n", available, head, tail, size);

	GEM_BUG_ON(available < 0);



	header = cmds[head];