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

[Yakir Yang <ykk@xxxxxxxxxxxxxx>]

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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