[PATCH v12 16/18] drm: bridge: analogix/dp: expand the wait time for looking AUX CH reply flag

[Jingoo Han]

On Thursday, December 24, 2015 10:23 AM, Yakir Yang wrote:
> 
> Hi Jingoo,
> 
> Okay, fine, I would drop this patch, until I found the the root cause.

OK, I see.

Best regards,
Jingoo Han

> 
> - Yakir
> 
> On 12/23/2015 11:10 PM, Jingoo Han wrote:
> > On Wednesday, December 23, 2015 9:51 PM, Yakir Yang wrote:
> >> On Rockchip platform, sometimes driver would failed at reading EDID
> >> message, and it's caused by the AUX reply flag wouldn't received under
> >> the 100*10us wait time.
> > The problem is specific for Rockchip platform.
> > Also, 1 ms is long time.
> > The best way is that your hardware engineers find the root cause.
> > I cannot understand why your engineers cannot find the root cause. :-(
> >
> >> But after expand the wait time a little, the AUX reply flag would be
> >> set, so maybe the wait time is a little critical. Besides the analogix
> >> dp book haven't reminded the standard wait for looking AUX reply flag,
> >> so I thought it's okay to expand the wait time.
> >>
> >> And the external wait time won't hurt Exynos DP too much, cause they
> >> wouldn't meet this problem, then driver would received the reply command
> >> very soon, so no more additional wait time would bring to Exynos platform.
> > Then, when loop time happens on Exynos platform, it will take long time
> > to return error.
> >
> >> Signed-off-by: Yakir Yang <ykk at rock-chips.com>
> >> ---
> >> Changes in v12:
> >> - Using another way to expand the AUX reply wait time (Jingoo)
> >>
> >> Changes in v11: None
> >> Changes in v10: None
> >> Changes in v9: None
> >> Changes in v8: None
> >> Changes in v7: None
> >> Changes in v6: None
> >> Changes in v5: None
> >> Changes in v4: None
> >> Changes in v3: None
> >> Changes in v2: None
> >>
> >>   drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 10 ++++------
> >>   1 file changed, 4 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> >> b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> >> index cba3ffd..8687eea 100644
> >> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> >> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> >> @@ -471,7 +471,7 @@ 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);
> >> @@ -479,14 +479,12 @@ 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? */
> >> -	reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
> >> -	while (!(reg & RPLY_RECEIV)) {
> >> -		timeout_loop++;
> >> -		if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
> >> +	timeout = jiffies + msecs_to_jiffies(5);
> >> +	while ((readl(dp->reg_base + ANALOGIX_DP_INT_STA) & RPLY_RECEIV) == 0) {
> >> +		if (time_after(jiffies, timeout)) {
> >>   			dev_err(dp->dev, "AUX CH command reply failed!\n");
> >>   			return -ETIMEDOUT;
> >>   		}
> >> -		reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
> > Sorry, I don't like your patch.
> >
> > The problem happens because of Rockchip platform.
> > So, you need to add workaround for only Rockchip platform.
> >
> > Just add new DT property and new variable for the value for wait time.
> > When, the probe is called, new wait time value is read from Rockchip DT file.
> > Then, the new wait time value can be written to the new variable.
> >
> >      new DT property: wait-time-aux
> >      new variable: wait_time_aux
> >
> >
> > If ( ) // New DT
> >      wait_time_aux = New DT;
> > else
> >      wait_time_aux = 10;
> >
> >
> >>   		usleep_range(10, 11);
> > If there is NO  new wait time value from DT file, the default value '10' is
> > used for sleep.
> >
> > But, if there is new wait time value from DT file, new wait time value
> > can be used for sleep.
> >
> >                   usleep_range(dp->wait_time_aux, dp->wait_time_aux + 1);
> >
> > What I want to say is that there should be NO effect on Exynos platform,
> > because of the hardware bug of Rockchip platform.
> >
> > Best regards,
> > Jingoo Han
> >
> >>   	}
> >>
> >> --
> >> 1.9.1
> >
> >
> >
> >