linux-kernel - Re: [PATCH v5 1/3] video: fbdev: atyfb: clarify ioremap() base and length used

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Date:	Wed, 8 Jul 2015 11:38:49 +0300
From:	Ville Syrjälä <syrjala@....fi>
To:	"Luis R. Rodriguez" <mcgrof@...e.com>
Cc:	Borislav Petkov <bp@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Ville Syrjälä 
	<ville.syrjala@...ux.intel.com>,
	Andy Lutomirski <luto@...capital.net>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-fbdev <linux-fbdev@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Dave Airlie <airlied@...hat.com>,
	Toshi Kani <toshi.kani@...com>,
	Suresh Siddha <sbsiddha@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Juergen Gross <jgross@...e.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Antonino Daplas <adaplas@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Rob Clark <robdclark@...il.com>,
	Mathias Krause <minipli@...glemail.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
	Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH v5 1/3] video: fbdev: atyfb: clarify ioremap() base and
 length used

On Tue, Jul 07, 2015 at 05:24:57PM -0700, Luis R. Rodriguez wrote:
> On Thu, Jul 2, 2015 at 4:23 PM, Luis R. Rodriguez <mcgrof@...e.com> wrote:
> > On Fri, Jun 26, 2015 at 12:30 AM, Borislav Petkov <bp@...e.de> wrote:
> >> On Fri, Jun 26, 2015 at 03:09:27AM +0200, Luis R. Rodriguez wrote:
> >>> Sure, mind this as a follow up patch if its too late?
> >>
> >> No need, you can send me an updated one - I'll replace it.
> >
> > Will do!
> 
> OK the commend I'm adding:
> 
> @@ -3489,6 +3489,15 @@ static int atyfb_setup_generic(struct pci_dev
> *pdev, struct fb_info *info,
> 
>         /* Map in frame buffer */
>         info->fix.smem_start = addr;
> +
> +       /*
> +        * The framebuffer is not always 8 MiB that's just the size of the
> +        * PCI BAR, this is later corrected for use with write-combining
> +        * helpers with aty_fudge_framebuffer_len() which will adjust the
> +        * framebuffer accordingly depending on the device.

That somehow gives me the impression that aty_fudge_framebuffer_len()
changes smem_len to match the framebuffer size, which it does
not.

Dunno, maybe something like this?
/*
 * The framebuffer is not always 8 MiB that's just the size of the
 * PCI BAR. We temporarily abuse smem_len here to store the size
 * of the BAR. aty_init() will later correct it to match the actual
 * framebuffer size.
 *
 * On devices that don't have the auxiliary register aperture, the
 * registers are housed at the top end of the framebuffer PCI BAR.
 * aty_fudge_framebuffer_len() is used to reduce smem_len to not
 * overlap with the registers.
 */

> We do this
> +        * to match semantics over ioremap calls on framebuffer devices
> +        * with with other drivers with the info->fix.smem_len.
> +        */
>         info->fix.smem_len = 0x800000;
> 
>         info->screen_base = ioremap(info->fix.smem_start, info->fix.smem_len);
> 
> Will respin.
> 
>  Luis

-- 
Ville Syrjälä
syrjala@....fi
http://www.sci.fi/~syrjala/
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