Re: [Linux-fbdev-devel] [PATCH] nvidiafb: allow ignoring EDID info

["Antonino A. Daplas" <adaplas@gmail.com>]

On Sat, 2007-02-24 at 10:16 +0100, Giuseppe Bilotta wrote:
> On 2/24/07, Antonino A. Daplas <adaplas@gmail.com> wrote:
> > On Fri, 2007-02-23 at 14:34 +0100, Giuseppe Bilotta wrote:
> > >
> > > The snowy is constant and abundant, and it seems to be independent of
> > > video size (640 through 1600) and screen occupation (single prompt
> > > line to fullscreen mc session) and usage.
> > >
> > > > I presume that X's nv driver or vesafb does not exhibit this problem?
> > >
> > > X's nv gives a very clean display, /unless/ I load nvidiafb before: if
> > > I modprobe nvidiafb (it's a module, and it's blacklisted precisely for
> > > this reason), then the screen is very snowy with X's nv too.
> > >
> >
> > Hmm..., I really don't know how to fix this except to look at Xorg's
> > code and look for a difference.
> 
> Keep in mind that setting nvidiafb to totally ignore the EDID (either
> by not compiling in EDID support or by using e.g. the ignoreedid patch
> I had proposed) the snow effect is extremely reduced,

I did not know that, just scanned the entire thread. Try this patch, it
makes use of fb_ddc_read*() which I believe has extra steps to prevent
display corruption.  It also incorporates Luca's i2c fix.

Tony

nvidiafb: Bring back generic ddc reading

Make nvidiafb use fb_ddc_read().  This patch was submitted before but was
reverted due to problems in a non-x86 platform.  This includes a fix for that
where ddc reading is bypassed if there is no DDC bus (duh).

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
---

 drivers/video/nvidia/nv_i2c.c |   44 ++---------------------------------------
 1 files changed, 2 insertions(+), 42 deletions(-)

diff --git a/drivers/video/nvidia/nv_i2c.c b/drivers/video/nvidia/nv_i2c.c
index b858897..b91d404 100644
--- a/drivers/video/nvidia/nv_i2c.c
+++ b/drivers/video/nvidia/nv_i2c.c
@@ -70,8 +70,6 @@ static int nvidia_gpio_getscl(void *data
 	if (VGA_RD08(par->PCIO, 0x3d5) & 0x04)
 		val = 1;
 
-	val = VGA_RD08(par->PCIO, 0x3d5);
-
 	return val;
 }
 
@@ -159,51 +157,13 @@ void nvidia_delete_i2c_busses(struct nvi
 
 }
 
-static u8 *nvidia_do_probe_i2c_edid(struct nvidia_i2c_chan *chan)
-{
-	u8 start = 0x0;
-	struct i2c_msg msgs[] = {
-		{
-		 .addr = 0x50,
-		 .len = 1,
-		 .buf = &start,
-		 }, {
-		     .addr = 0x50,
-		     .flags = I2C_M_RD,
-		     .len = EDID_LENGTH,
-		     },
-	};
-	u8 *buf;
-
-	if (!chan->par)
-		return NULL;
-
-	buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
-	if (!buf) {
-		dev_warn(&chan->par->pci_dev->dev, "Out of memory!\n");
-		return NULL;
-	}
-	msgs[1].buf = buf;
-
-	if (i2c_transfer(&chan->adapter, msgs, 2) == 2)
-		return buf;
-	dev_dbg(&chan->par->pci_dev->dev, "Unable to read EDID block.\n");
-	kfree(buf);
-	return NULL;
-}
-
 int nvidia_probe_i2c_connector(struct fb_info *info, int conn, u8 **out_edid)
 {
 	struct nvidia_par *par = info->par;
 	u8 *edid = NULL;
-	int i;
 
-	for (i = 0; i < 3; i++) {
-		/* Do the real work */
-		edid = nvidia_do_probe_i2c_edid(&par->chan[conn - 1]);
-		if (edid)
-			break;
-	}
+	if (par->chan[conn - 1].par)
+		edid = fb_ddc_read(&par->chan[conn - 1].adapter);
 
 	if (!edid && conn == 1) {
 		/* try to get from firmware */