Hi Sekhar,
On Fri, Aug 17, 2012 at 12:15:01, Nori, Sekhar wrote:
> Hi Prakash,
>
> On 8/14/2012 6:53 PM, Manjunathappa, Prakash wrote:
> > Wait for active frame transfer to complete after disabling LCDC.
> > At the same this wait is not be required when there are sync and
> > underflow errors.
> > More information on disable and reset sequence can be found in
> > section 13.4.6 of AM335x TRM @www.ti.com/am335x.
> >
> > Signed-off-by: Manjunathappa, Prakash <prakash.pm@xxxxxx>
> > ---
> > Applies on top of fbdev-next of Florian Tobias Schandinat's tree.
> > Since v2:
> > Optimized the lcd_disable_raster function.
> > Since v1:
> > Changed the commit message, also added link to hardware specification.
> >
> > drivers/video/da8xx-fb.c | 49 ++++++++++++++++++++++++++++++++++++---------
> > 1 files changed, 39 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/video/da8xx-fb.c b/drivers/video/da8xx-fb.c
> > index 7ae9d53..cb696ff 100644
> > --- a/drivers/video/da8xx-fb.c
> > +++ b/drivers/video/da8xx-fb.c
> > @@ -48,6 +48,7 @@
> > #define LCD_PL_LOAD_DONE BIT(6)
> > #define LCD_FIFO_UNDERFLOW BIT(5)
> > #define LCD_SYNC_LOST BIT(2)
> > +#define LCD_FRAME_DONE BIT(0)
> >
> > /* LCD DMA Control Register */
> > #define LCD_DMA_BURST_SIZE(x) ((x) << 4)
> > @@ -288,13 +289,41 @@ static inline void lcd_enable_raster(void)
> > }
> >
> > /* Disable the Raster Engine of the LCD Controller */
> > -static inline void lcd_disable_raster(void)
> > +static inline void lcd_disable_raster(bool wait_for_frame_done)
> > {
> > u32 reg;
> > + u32 stat_reg = LCD_STAT_REG;
> > + u32 loop_cnt = 0;
> >
> > reg = lcdc_read(LCD_RASTER_CTRL_REG);
> > if (reg & LCD_RASTER_ENABLE)
> > lcdc_write(reg & ~LCD_RASTER_ENABLE, LCD_RASTER_CTRL_REG);
> > +
> > + if (lcd_revision == LCD_VERSION_2)
> > + stat_reg = LCD_RAW_STAT_REG;
> > +
> > + if (wait_for_frame_done) {
> > + /*
> > + * 50 milli seconds should be sufficient for a frame to
> > + * complete
> > + */
> > + loop_cnt = 50;
> > + while (!(lcdc_read(stat_reg) & LCD_FRAME_DONE)) {
> > + /* Handle timeout */
> > + if (unlikely(0 == --loop_cnt)) {
> > + pr_err("LCD Controller timed out\n");
> > + break;
> > + }
> > + mdelay(1);
> > + }
> > + }
>
> The TRM you referenced in the patch description suggests waiting for
> frame done interrupt. Can we actually wait for the interrupt here
> instead of busy looping?
>
I agree, will submit next version of patch considering above.
Thanks,
Prakash
> Thanks,
> Sekhar
>
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