linux-kernel - Re: [PATCH] video: ARM CLCD: Added support for FBIO

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Date:	Tue, 03 Mar 2015 10:01:26 +0000
From:	Pawel Moll <pawel.moll@....com>
To:	Arun Ramamurthy <arun.ramamurthy@...adcom.com>
Cc:	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <Mark.Rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	Dmitry Torokhov <dtor@...gle.com>,
	Anatol Pomazau <anatol@...gle.com>,
	Jonathan Richardson <jonathar@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Ray Jui <rjui@...adcom.com>,
	"bcm-kernel-feedback-list@...adcom.com" 
	<bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH] video: ARM CLCD: Added support for FBIO_WAITFORVSYNC

On Mon, 2015-03-02 at 19:09 +0000, Arun Ramamurthy wrote:
> On 15-03-02 08:00 AM, Pawel Moll wrote:
> > On Wed, 2015-02-25 at 21:01 +0000, Arun Ramamurthy wrote:
> >> Added ioctl and interrupt handler functions to support FBIO_WAITFORVSYNC
> >> Also corrected documentation to make interrupts and interrupt-names
> >> optional as they are not required properties.
> >
> > You may not be aware of this fact, but its the "documentation" what
> > defines what properties are required...
> >
> Pawel, I was not aware of that. Since the driver code did not require 
> the interrupts or interrupt-names bindings to load properly, I moved it 
> out of the required properties. I can remove that change.

Cool. Drivers don't have to use all available properties :-) The
interrupt names are required because CLCD can be wired up with a single,
combined interrupt or with 4 separate interrupt lines (see "A.4. On-chip
signals", in the TRM) and the binding has to provide ways of describing
this. Yes, one could say "1 number == combined, 4 numbers == split", but
I personally prefer to be explicit than implicit.

Just request the interrupt by name and you'll be fine.

> Any other comments on this change? Thanks

I have no experience with the vsync ioctl, so can't really comment on
it. One minor thing I did spot is your use of curly brackets in one of
the switch cases:

On Wed, 2015-02-25 at 21:01 +0000, Arun Ramamurthy wrote:
@@ -466,6 +468,73 @@ static int clcdfb_pan_display(struct fb_var_screeninfo *var,
>  	return 0;
>  }
>  
> +static int clcdfb_ioctl(struct fb_info *info,
> +			unsigned int cmd, unsigned long args)
> +{
> +	struct clcd_fb *fb = to_clcd(info);
> +	int retval = 0;
> +	u32 val, ienb_val;
> +
> +	switch (cmd) {
> +	case FBIO_WAITFORVSYNC:{

In the line above...

> +		if (fb->lcd_irq <= 0) {
> +			retval = -EINVAL;
> +			break;
> +		}
> +		/* disable Vcomp interrupts */
> +		ienb_val = readl(fb->regs + fb->off_ienb);
> +		ienb_val &= ~CLCD_PL111_IENB_VCOMP;
> +		writel(ienb_val, fb->regs + fb->off_ienb);
> +
> +		/* clear Vcomp interrupt */
> +		writel(CLCD_PL111_IENB_VCOMP, fb->regs + CLCD_PL111_ICR);
> +
> +		/* Generate Interrupt at the start of Vsync */
> +		reinit_completion(&fb->wait);
> +		val = readl(fb->regs +  fb->off_cntl);
> +		val &= ~(CNTL_LCDVCOMP(3));
> +		writel(val, fb->regs + fb->off_cntl);
> +
> +		/* enable Vcomp interrupt */
> +		ienb_val = readl(fb->regs + fb->off_ienb);
> +		ienb_val |= CLCD_PL111_IENB_VCOMP;
> +		writel(ienb_val, fb->regs + fb->off_ienb);
> +		if (!wait_for_completion_interruptible_timeout
> +			(&fb->wait, HZ/10))
> +			retval = -ETIMEDOUT;
> +		break;
> +	}

... and here.

Not sure it's needed?

Pawel


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