V4L/DVB (5917): ivtv: improve mailbox responsiveness.

First try polling for the result of a mailbox command, then
switch to a test/sleep loop. Also reduce the sleep time from 10 ms
to 1 ms. Improves the responsiveness of the mailbox handling.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 11 insertions, 3 deletions

diff --git a/drivers/media/video/ivtv/ivtv-mailbox.c b/drivers/media/video/ivtv/ivtv-mailbox.c
index 814a673712b3..5e3b679202ae 100644
--- a/drivers/media/video/ivtv/ivtv-mailbox.c
+++ b/drivers/media/video/ivtv/ivtv-mailbox.c
@@ -40,6 +40,7 @@
 #define API_HIGH_VOL     (1 << 5)       /* High volume command (i.e. called during encoding or decoding) */
 #define API_NO_WAIT_MB   (1 << 4)       /* Command may not wait for a free mailbox */
 #define API_NO_WAIT_RES  (1 << 5)       /* Command may not wait for the result */
+#define API_NO_POLL      (1 << 6)       /* Avoid pointless polling */
 
 struct ivtv_api_info {
         int flags;              /* Flags, see above */
@@ -51,7 +52,7 @@ struct ivtv_api_info {
 static const struct ivtv_api_info api_info[256] = {
         /* MPEG encoder API */
         API_ENTRY(CX2341X_ENC_PING_FW,                  API_FAST_RESULT),
-        API_ENTRY(CX2341X_ENC_START_CAPTURE,            API_RESULT),
+        API_ENTRY(CX2341X_ENC_START_CAPTURE,            API_RESULT | API_NO_POLL),
         API_ENTRY(CX2341X_ENC_STOP_CAPTURE,             API_RESULT),
         API_ENTRY(CX2341X_ENC_SET_AUDIO_ID,             API_CACHE),
         API_ENTRY(CX2341X_ENC_SET_VIDEO_ID,             API_CACHE),
@@ -96,7 +97,7 @@ static const struct ivtv_api_info api_info[256] = {
 
         /* MPEG decoder API */
         API_ENTRY(CX2341X_DEC_PING_FW,                  API_FAST_RESULT),
-        API_ENTRY(CX2341X_DEC_START_PLAYBACK,           API_RESULT),
+        API_ENTRY(CX2341X_DEC_START_PLAYBACK,           API_RESULT | API_NO_POLL),
         API_ENTRY(CX2341X_DEC_STOP_PLAYBACK,            API_RESULT),
         API_ENTRY(CX2341X_DEC_SET_PLAYBACK_SPEED,       API_RESULT),
         API_ENTRY(CX2341X_DEC_STEP_VIDEO,               API_RESULT),
@@ -290,6 +291,13 @@ static int ivtv_api_call(struct ivtv *itv, int cmd, int args, u32 data[])
         /* Get results */
         then = jiffies;
 
+        if (!(flags & API_NO_POLL)) {
+                /* First try to poll, then switch to delays */
+                for (i = 0; i < 100; i++) {
+                        if (readl(&mbox->flags) & IVTV_MBOX_FIRMWARE_DONE)
+                                break;
+                }
+        }
         while (!(readl(&mbox->flags) & IVTV_MBOX_FIRMWARE_DONE)) {
                 if (jiffies - then > api_timeout) {
                         IVTV_DEBUG_WARN("Could not get result (%s)\n", api_info[cmd].name);
@@ -301,7 +309,7 @@ static int ivtv_api_call(struct ivtv *itv, int cmd, int args, u32 data[])
                 if (flags & API_NO_WAIT_RES)
                         mdelay(1);
                 else
-                        ivtv_msleep_timeout(10, 0);
+                        ivtv_msleep_timeout(1, 0);
         }
         if (jiffies - then > msecs_to_jiffies(100))
                 IVTV_DEBUG_WARN("%s took %u jiffies\n",