Subject: GPIO regression in Linux next caused by syscon change

From: [email-masked] (Tony Lindgren)
Date: Mon, 15 Feb 2016 10:06:36 -0800

* Tony Lindgren <[email-masked]> [160215 08:49]:
> * Philipp Zabel <[email-masked]> [160215 08:17]:
> > Am Montag, den 15.02.2016, 08:01 -0800 schrieb Tony Lindgren:
> > > * Philipp Zabel <[email-masked]> [160214 11:24]:
> > > > I've just replaced the of_iomap() call with an open coded version,
> > > > calling of_address_to_resource() and ioremap() directly. That was
> > > > needed so I can use the struct resource returned by
> > > > of_address_to_resource() to set the syscon_config.max_register. I
> > > > don't see where this could cause resource overlap. Does just setting
> > > > syscon_config.max_register to zero again make the problem disappear?
> > > 
> > > Yes commenting out the syscon_config.max_register line in your patch
> > > makes things work again.
> > > 
> > > So what does that tell us about the problem?
> > 
> > Maybe some out of bounds writes that previously worked are now catched
> > by the max_register check in regmap_writable and regmap_write returns
> > -EIO instead of the write being executed.
> 
> Hmm weird that something like that would not produce errors?
> 
> > Is there any omap_ctrl_write?() call with an offset > 0x32c into
> > scm_conf?
> 
> Indeed, that's where things go wrong. Adding Tero to Cc, something
> is wrong there.

Something like this might fix it? Needs to be tested to see if it
happens on other omaps.

Tero, got any better ideas?

Regards,

Tony

8< -------------------
--- a/arch/arm/mach-omap2/control.c
+++ b/arch/arm/mach-omap2/control.c
@@ -167,15 +167,23 @@ u16 omap_ctrl_readw(u16 offset)
 u32 omap_ctrl_readl(u16 offset)
 {
 	u32 val;
+	int err;
 
 	offset &= 0xfffc;
-	if (!omap2_ctrl_syscon)
-		val = readl_relaxed(omap2_ctrl_base + offset);
-	else
-		regmap_read(omap2_ctrl_syscon, omap2_ctrl_offset + offset,
-			    &val);
+	if (omap2_ctrl_syscon) {
+		err = regmap_read(omap2_ctrl_syscon,
+				  omap2_ctrl_offset + offset, &val);
+		if (!err)
+			return val;
+	}
+
+	if (WARN(!omap2_ctrl_base,
+		 "syscon out of range for offset 0x%x, no omap2_ctrl_base?\n",
+		    offset)) {
+		return 0;
+	}
 
-	return val;
+	return readl_relaxed(omap2_ctrl_base + offset);
 }
 
 void omap_ctrl_writeb(u8 val, u16 offset)
@@ -206,12 +214,23 @@ void omap_ctrl_writew(u16 val, u16 offset)
 
 void omap_ctrl_writel(u32 val, u16 offset)
 {
+	int err;
+
 	offset &= 0xfffc;
-	if (!omap2_ctrl_syscon)
-		writel_relaxed(val, omap2_ctrl_base + offset);
-	else
-		regmap_write(omap2_ctrl_syscon, omap2_ctrl_offset + offset,
-			     val);
+	if (omap2_ctrl_syscon) {
+		err = regmap_write(omap2_ctrl_syscon,
+				   omap2_ctrl_offset + offset, val);
+		if (!err)
+			return;
+	}
+
+	if (WARN(!omap2_ctrl_base,
+		 "syscon out of range for offset 0x%x, no omap2_ctrl_base?\n",
+		    offset)) {
+		return;
+	}
+
+	writel_relaxed(val, omap2_ctrl_base + offset);
 }
 
 #ifdef CONFIG_ARCH_OMAP3
@@ -724,9 +743,6 @@ int __init omap_control_init(void)
 				if (ret)
 					return ret;
 			}
-
-			iounmap(omap2_ctrl_base);
-			omap2_ctrl_base = NULL;
 		} else {
 			/* No scm_conf found, direct access */
 			ret = omap2_clk_provider_init(np, data->index, NULL,