Hi Mellis,
The register masks are set up for an 8bit byte operation. If you use a
32bit read/write (readl/writel) you get very different results on a big
endian system (SPARC) when you apply a byte mask. This is why you need to
use 8bit (readb/writeb) operations.
In addition, using 8bit read/write will prevent corruption of any of the
next three registers if they have different read/write information.
Regards
Mark Fortescue.
On Wed, 16 Feb 2005, Meelis Roos wrote:
> MF> This patch fixes an error in the blanking code for the GCThree SBUS
> MF> video card. Now I get a logo and black screen, not just a blank (no
> MF> video) screen. It is a trivual fix that has taken too long to identify as
> MF> it is such a small typing error during the rewriting of the code for
> MF> the new frame buffer system introduced in the 2.5 series kernels.
>
> The "val &= ~CG3_CR_ENABLE_VIDEO;" bit is in main kernel now. But what
> about the readl/writel vs readb/writeb - is this also needed? Why?
>
> --
> Meelis Roos
>
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