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?
Thanks,
Sekhar
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