G5 Quad hangs early on 4.20.2 / 5.0-rc2+

[Tobias Ulmer]

On Fri, Jan 18, 2019 at 09:32:07AM +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2019-01-17 at 10:42 +0100, Tobias Ulmer wrote:
> > On Wed, Jan 16, 2019 at 12:15:14PM +1100, Benjamin Herrenschmidt wrote:
> > > On Tue, 2019-01-15 at 23:49 +0100, Tobias Ulmer wrote:
> > > > Hi,
> > > > 
> > > > both the latest stable 4.20.2 and 5.0 rc2+ hang early on the G5 Quad.
> > > > 
> > > > Surely I'm not the first to run into this, but I couldn't find any
> > > > discussion or bug report. Sorry if you're already aware.
> > > > 
> > > > You can see it hang here (5.0 rc2+, 4.20.2 is nearly identical) until
> > > > the watchdog triggers a reboot:
> > > > 
> > > > https://i.imgur.com/UiCVRuG.jpg
> > > > 
...
> I'll be back on monday or tuesday, let me know where you got up to then
> and I'll take it from there. Also email me your .config please.


Hi,

this was caused by 5c63e407aaabb0464236cfc6279a2d79aede7073
(fbdev: Convert to using %pOFn instead of device_node.name)

name can't be NULL into offb_init_fb, there's a printk and the call to
offb_init_palette_hacks where name is matched against OF device names.

With the partial revert below, both 5.0-rc2+ and 4.20 are happy.

diff --git a/drivers/video/fbdev/offb.c b/drivers/video/fbdev/offb.c
index 31f769d67195..77c0a2f45b3b 100644
--- a/drivers/video/fbdev/offb.c
+++ b/drivers/video/fbdev/offb.c
@@ -419,13 +419,9 @@ static void __init offb_init_fb(const char *name,
 	var = &info->var;
 	info->par = par;
 
-	if (name) {
-		strcpy(fix->id, "OFfb ");
-		strncat(fix->id, name, sizeof(fix->id) - sizeof("OFfb "));
-		fix->id[sizeof(fix->id) - 1] = '\0';
-	} else
-		snprintf(fix->id, sizeof(fix->id), "OFfb %pOFn", dp);
-
+	strcpy(fix->id, "OFfb ");
+	strncat(fix->id, name, sizeof(fix->id) - sizeof("OFfb "));
+	fix->id[sizeof(fix->id) - 1] = '\0';
 
 	var->xres = var->xres_virtual = width;
 	var->yres = var->yres_virtual = height;
@@ -648,7 +644,7 @@ static void __init offb_init_nodriver(struct device_node *dp, int no_real_node)
 		/* kludge for valkyrie */
 		if (strcmp(dp->name, "valkyrie") == 0)
 			address += 0x1000;
-		offb_init_fb(no_real_node ? "bootx" : NULL,
+		offb_init_fb(no_real_node ? "bootx" : dp->name,
 			     width, height, depth, pitch, address,
 			     foreign_endian, no_real_node ? NULL : dp);
 	}