[PATCH 7/7] ARM i.MX51 babbage: Add display support

[Marek Vasut]

Dear Fabio Estevam,

> On Tue, Jan 8, 2013 at 2:41 PM, Fabio Estevam <festevam at gmail.com> wrote:
> > Hi Sascha,
> > 
> > On Mon, Nov 12, 2012 at 1:23 PM, Sascha Hauer <s.hauer at pengutronix.de> 
wrote:
> >> The babbage board has a DVI-I output which allows to output analog
> >> and digital signals simultaneously. This patch adds support for it
> >> to the devicetree. The DDC signals are not wired up on the board, so
> >> DRM will fall back on default VESA modes.
> >> 
> >> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> > 
> > I am running linux-next 20130108, which has this patch applied and I
> 
> > get the following on my mx51babbage:
> Ok, good news. I see a nice penguin on my monitor now.
> 
> Discussed with Marek and he proposed a quick workaround:
> 
> --- a/drivers/staging/imx-drm/ipuv3-crtc.c
> +++ b/drivers/staging/imx-drm/ipuv3-crtc.c
> @@ -343,6 +343,11 @@ static irqreturn_t ipu_irq_handler(int irq, void
> *dev_id) {
>         struct ipu_crtc *ipu_crtc = dev_id;
> 
> +       if (!ipu_crtc->imx_crtc) {
> +               pr_err("Spurious IPU IRQ\n");
> +               return IRQ_HANDLED;
> +       }
> +
>         imx_drm_handle_vblank(ipu_crtc->imx_crtc);
> 
>         if (ipu_crtc->newfb) {
> 
> It seems that this issue happened because bootloader leaves the IPU turned
> on.

To elaborate more on this stuff:

491         ipu_crtc->irq = ipu_idmac_channel_irq(ipu, ipu_crtc->ipu_ch,
492                         IPU_IRQ_EOF);
493         ret = devm_request_irq(ipu_crtc->dev, ipu_crtc->irq, 
ipu_irq_handler, 0,
494                         "imx_drm", ipu_crtc);
495         if (ret < 0) {
496                 dev_err(ipu_crtc->dev, "irq request failed with %d.\n", 
ret);
497                 goto err_out;
498         }
499 
500         disable_irq(ipu_crtc->irq);

This code in drivers/staging/imx-drm/ipuv3-crtc.c is broken. If the IPU is on, 
it produces an interrupt before the driver is fully set up. I didn't produce a 
patch yet, I think I might offload this to someone else. Volunteers?

Best regards,
Marek Vasut