Re: [PATCH v4 3/5] powerpc/mpc5121: shared DIU framebuffer support
From: Tabi Timur-B04825 <hidden>
Date: 2011-12-15 17:27:53
On Fri, Jul 23, 2010 at 9:00 AM, Anatolij Gustschin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
@@ -1471,7 +1476,9 @@ static int __devinit fsl_diu_probe(struct of_device *ofdev,goto error2; } - out_be32(&dr.diu_reg->diu_mode, 0); /* disable DIU anyway*/ + diu_mode = in_be32(&dr.diu_reg->diu_mode); + if (diu_mode != MFB_MODE1) + out_be32(&dr.diu_reg->diu_mode, 0); /* disable DIU */
Anatolij,
I know this patch is old, but I just noticed something odd about it
that I need your help with.
In the above snippet, you test for != MFB_MODE1. My understanding is
that U-boot only supports modes 0 and 1, never modes 2 or 3. So
diu_mode can only ever be 0 or 1. That means that that the above code
is equivalent to:
diu_mode = in_be32(&dr.diu_reg->diu_mode);
if (diu_mode = 0)
out_be32(&dr.diu_reg->diu_mode, 0); /* disable DIU */
which is silly, because now we're writing 0 to diu_mode only if it's already 0.
Am I missing something?
--
Timur Tabi
Linux kernel developer at Freescale