Re: [PATCH v3 2/3] drm/bridge: analogix_dp: use jiffies to simulate timeout loop

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Hi Sean,


On 09/12/2016 09:51 PM, Sean Paul wrote:
On Fri, Sep 9, 2016 at 5:44 AM, Yakir Yang <ykk@xxxxxxxxxxxxxx> wrote:
Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
---
Changes in v3:
- Suggested by Sean

Changes in v2: None

  drivers/gpu/drm/bridge/analogix/analogix_dp_core.h |  3 ++-
  drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c  | 18 +++++++++---------
  2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index a15f076..d564e90 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
@@ -16,10 +16,11 @@
  #include <drm/drm_crtc.h>
  #include <drm/drm_dp_helper.h>

-#define DP_TIMEOUT_LOOP_COUNT 100
  #define MAX_CR_LOOP 5
  #define MAX_EQ_LOOP 5

+#define DP_TIMEOUT_LOOP_MS                     msecs_to_jiffies(1)
The name suggests the units here are ms, but you're storing jiffies.
Do the msecs_to_jiffies conversion down below.

I suddenly realized that 'analogix_dp_core.c' also used the 'DP_TIMEOUT_LOOP_COUNT' macros, and 'analogix_dp_core.c' have four kinds of timeout,
  - DP_TIMEOUT_LOOP_COUNT * 1us
  - DP_TIMEOUT_LOOP_COUNT * 10us
  - DP_TIMEOUT_LOOP_COUNT * 100us
  - DP_TIMEOUT_LOOP_COUNT * 1000us

I may guess it's not necessary to replace the 'DP_TIMEOUT_LOOP_COUNT' now :-)

- Yakir


+
  /* DP_MAX_LANE_COUNT */
  #define DPCD_ENHANCED_FRAME_CAP(x)             (((x) >> 7) & 0x1)
  #define DPCD_MAX_LANE_COUNT(x)                 ((x) & 0x1f)
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index a4d17b8..15a4cf0 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -335,7 +335,7 @@ void analogix_dp_set_analog_power_down(struct analogix_dp_device *dp,
  void analogix_dp_init_analog_func(struct analogix_dp_device *dp)
  {
         u32 reg;
-       int timeout_loop = 0;
+       unsigned long timeout;

         analogix_dp_set_analog_power_down(dp, POWER_ALL, 0);

@@ -350,9 +350,9 @@ void analogix_dp_init_analog_func(struct analogix_dp_device *dp)
         if (analogix_dp_get_pll_lock_status(dp) == PLL_UNLOCKED) {
                 analogix_dp_set_pll_power_down(dp, 0);

+               timeout = jiffies + DP_TIMEOUT_LOOP_MS;
timeout = jiffies + msecs_to_jiffies(DP_TIMEOUT_LOOP_MS);

                 while (analogix_dp_get_pll_lock_status(dp) == PLL_UNLOCKED) {
-                       timeout_loop++;
-                       if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
+                       if (time_after(jiffies, timeout)) {
                                 dev_err(dp->dev, "failed to get pll lock status\n");
                                 return;
                         }
@@ -501,7 +501,7 @@ int analogix_dp_start_aux_transaction(struct analogix_dp_device *dp)
  {
         int reg;
         int retval = 0;
-       int timeout_loop = 0;
+       unsigned long timeout;

         /* Enable AUX CH operation */
         reg = readl(dp->reg_base + ANALOGIX_DP_AUX_CH_CTL_2);
@@ -509,10 +509,10 @@ int analogix_dp_start_aux_transaction(struct analogix_dp_device *dp)
         writel(reg, dp->reg_base + ANALOGIX_DP_AUX_CH_CTL_2);

         /* Is AUX CH command reply received? */
+       timeout = jiffies + DP_TIMEOUT_LOOP_MS;
         reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
         while (!(reg & RPLY_RECEIV)) {
-               timeout_loop++;
-               if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
+               if (time_after(jiffies, timeout)) {
                         dev_err(dp->dev, "AUX CH command reply failed!\n");
                         return -ETIMEDOUT;
                 }
@@ -1055,7 +1055,7 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
  {
         u32 reg;
         u8 *buffer = msg->buffer;
-       int timeout_loop = 0;
+       unsigned long timeout;
         unsigned int i;
         int num_transferred = 0;

@@ -1123,10 +1123,10 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,

         /* Is AUX CH command reply received? */
         /* TODO: Wait for an interrupt instead of looping? */
+       timeout = jiffies + DP_TIMEOUT_LOOP_MS;
         reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
         while (!(reg & RPLY_RECEIV)) {
-               timeout_loop++;
-               if (timeout_loop > DP_TIMEOUT_LOOP_COUNT) {
+               if (time_after(jiffies, timeout)) {
                         dev_err(dp->dev, "AUX CH command reply failed!\n");
                         return -ETIMEDOUT;
                 }
--
1.9.1






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