Re: [PATCH v3 10/11] [ARM] tegra: Add framebuffer driver

[Jaya Kumar <jayakumar.lkml@gmail.com>]

On Tue, Jun 15, 2010 at 5:10 AM, Erik Gilling <konkers@android.com> wrote:
> diff --git a/drivers/video/tegrafb.c b/drivers/video/tegrafb.c
> new file mode 100644
> index 0000000..47b2d42
> --- /dev/null
> +++ b/drivers/video/tegrafb.c

> +/* palette attary used by the fbcon */
> +u32 pseudo_palette[16];

attary

> +
> +irqreturn_t tegra_fb_irq(int irq, void *ptr)
> +{
> +       struct fb_info *info = ptr;
> +       struct tegra_fb_info *tegra_fb = info->par;
> +
> +       u32 reg = tegra_fb_readl(tegra_fb, DC_CMD_INT_STATUS);
> +       tegra_fb_writel(tegra_fb, reg, DC_CMD_INT_STATUS);
> +
> +       tegra_fb->wait_condition = 1;
> +       wake_up(&tegra_fb->event_wq);
> +       return IRQ_HANDLED;
> +}
> +
> +static int tegra_fb_wait_for_event(struct tegra_fb_info *tegra_fb,
> +       unsigned long timeout, u32 irq_mask)
> +{
> +       u32 reg;
> +
> +       tegra_fb->wait_condition = 0;
> +
> +       reg = tegra_fb_readl(tegra_fb, DC_CMD_INT_MASK);
> +       reg |= irq_mask;
> +       tegra_fb_writel(tegra_fb, reg, DC_CMD_INT_MASK);
> +
> +       /* Clear any pending interrupt */
> +       tegra_fb_writel(tegra_fb, irq_mask, DC_CMD_INT_STATUS);
> +
> +       tegra_fb_writel(tegra_fb, irq_mask, DC_CMD_INT_ENABLE);
> +
> +       /* Wait for the irq to fire */
> +       wait_event_interruptible_timeout(tegra_fb->event_wq,
> +               tegra_fb->wait_condition, timeout);
> +
> +       tegra_fb_writel(tegra_fb, 0, DC_CMD_INT_ENABLE);
> +
> +       if (!tegra_fb->wait_condition) {
> +               pr_warning("%s: wait for vsync timed out\n", __func__);
> +               return -ETIMEDOUT;
> +       }
> +       return 0;
> +}

Apologies for the incremental review. The wait_condition code above
looks odd to me. Typically, we just test the return value of
wait_event_interruptible_timeout to see whether it timed out (returns
0 if so). But I guess the above approach works as well.

> +               if (tegra_fb_wait_for_event(tegra_fb, HZ/10, DC_INT_FRAME_END))

I still didn't follow how tegra_fb_activate is using the -ETIMEDOUT
return value from the wait, it seems like it is just ignored. You are
also doing stuff like HZ/10 and you might prefer to use
msecs_to_jiffies.

Thanks,
jaya