[PATCH v2] drm/xe: Change pcode timeout to 50msec while polling again

[Lucas De Marchi]

On Wed, May 08, 2024 at 09:13:28AM GMT, Himal Prasad Ghimiray wrote:
>Polling is initially attempted with timeout_base_ms enabled for
>preemption, and if it exceeds this timeframe, another attempt is made
>without preemption, allowing an additional 50 ms before timing out.
>
>Display driver can request for timeout of 3 msec, hence modify the
>warning condition.

this seems like a separate fix?

afaics below we have:

1) fix the warning to consider the display case ... and shouldn't the
    warning be before the first pcode_try_request()? Why do we want to
    warn before a fixed-duration rather than before the variable duration
    passed as argument?

2) change the second timeout to be a fixed 50 msec rather than 1msec so
    it follows what was actually documented in that comment.

or maybe I'm missing something here... could you clarify?

Lucas De Marchi

>
>v2
>- Rebase
>
>Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
>---
> drivers/gpu/drm/xe/xe_pcode.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_pcode.c b/drivers/gpu/drm/xe/xe_pcode.c
>index c010ef16fbf5..2771eed1e45f 100644
>--- a/drivers/gpu/drm/xe/xe_pcode.c
>+++ b/drivers/gpu/drm/xe/xe_pcode.c
>@@ -10,6 +10,7 @@
>
> #include <drm/drm_managed.h>
>
>+#include "xe_assert.h"
> #include "xe_device.h"
> #include "xe_gt.h"
> #include "xe_mmio.h"
>@@ -124,6 +125,8 @@ static int pcode_try_request(struct xe_gt *gt, u32 mbox,
> {
> 	int slept, wait = 10;
>
>+	xe_gt_assert(gt, timeout_us > 0);
>+
> 	for (slept = 0; slept < timeout_us; slept += wait) {
> 		if (locked)
> 			*status = pcode_mailbox_rw(gt, mbox, &request, NULL, 1, true,
>@@ -166,7 +169,7 @@ static int pcode_try_request(struct xe_gt *gt, u32 mbox,
> int xe_pcode_request(struct xe_gt *gt, u32 mbox, u32 request,
> 		      u32 reply_mask, u32 reply, int timeout_base_ms)
> {
>-	u32 status;
>+	u32 status = 0;
> 	int ret;
>
> 	mutex_lock(&gt->pcode.lock);
>@@ -188,10 +191,10 @@ int xe_pcode_request(struct xe_gt *gt, u32 mbox, u32 request,
> 	 */
> 	drm_err(&gt_to_xe(gt)->drm,
> 		"PCODE timeout, retrying with preemption disabled\n");
>-	drm_WARN_ON_ONCE(&gt_to_xe(gt)->drm, timeout_base_ms > 1);
>+	drm_WARN_ON_ONCE(&gt_to_xe(gt)->drm, timeout_base_ms > 3);
> 	preempt_disable();
> 	ret = pcode_try_request(gt, mbox, request, reply_mask, reply, &status,
>-				true, timeout_base_ms * 1000, true);
>+				true, 50 * 1000, true);
> 	preempt_enable();
>
> out:
>-- 
>2.25.1
>