[PATCH v1] drm/xe/guc: Fix h2g_write usage of GUC_CTB_MSG_MAX_LEN

[Alan Previn]

In the ABI header, GUC_CTB_MSG_MIN_LEN is '1' because
GUC_CTB_HDR_LEN is 1. This aligns with H2G/G2H CTB specification
where all command formats are defined in units of dwords so that '1'
is a dword. Accordingly, GUC_CTB_MSG_MAX_LEN is 256-1 (i.e. 255
dwords). However, h2g_write was incorrectly assuming that
GUC_CTB_MSG_MAX_LEN was in bytes. Fix this.

Signed-off-by: Alan Previn <alan.previn.teres.alexis at intel.com>
---
 drivers/gpu/drm/xe/xe_guc_ct.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 137c184df487..8e9df6052b02 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -401,7 +401,7 @@ static int h2g_write(struct xe_guc_ct *ct, const u32 *action, u32 len,
 {
 	struct xe_device *xe = ct_to_xe(ct);
 	struct guc_ctb *h2g = &ct->ctbs.h2g;
-	u32 cmd[GUC_CTB_MSG_MAX_LEN / sizeof(u32)];
+	u32 cmd[GUC_CTB_MSG_MAX_LEN];
 	u32 cmd_len = len + GUC_CTB_HDR_LEN;
 	u32 cmd_idx = 0, i;
 	u32 tail = h2g->info.tail;
@@ -409,7 +409,7 @@ static int h2g_write(struct xe_guc_ct *ct, const u32 *action, u32 len,
 							 tail * sizeof(u32));
 
 	lockdep_assert_held(&ct->lock);
-	XE_BUG_ON(len * sizeof(u32) > GUC_CTB_MSG_MAX_LEN);
+	XE_BUG_ON(len > GUC_CTB_MSG_MAX_LEN - 1);
 	XE_BUG_ON(tail > h2g->info.size);
 
 	/* Command will wrap, zero fill (NOPs), return and check credits again */

base-commit: 9f49c413b187c00f223eaf1e8dbe2c1a97c9954b
-- 
2.39.0