Re: [BUG] simplefb not showing any output

[David Herrmann <dh.herrmann@gmail.com>]

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Hi Tom

On Sat, Sep 7, 2013 at 1:47 PM, Tom Gundersen <teg@jklm.no> wrote:
> On Sat, Sep 7, 2013 at 1:18 PM, David Herrmann <dh.herrmann@gmail.com> wrote:
>> On Sat, Sep 7, 2013 at 11:26 AM, Tom Gundersen <teg@jklm.no> wrote:
>>> On Fri, Sep 6, 2013 at 6:11 PM, Tom Gundersen <teg@jklm.no> wrote:
>>>> The driver seems to load ok, but sadly it does not give any output. If
>>>> I boot via the gummiboot menu the screen remains black, and if I don't
>>>> enter the gummiboot menu the screen remains grey (it is a Mac).
>>>
>>> My apologies, this was a config error (I somehow ended up with
>>> FRAMEBUFFER_CONSOLE=m, which works fine with inteldrmfb, but obviously
>>> not with any of the compiled in ones).
>>
>> Good, I almost went crazy looking for an error. Does that mean
>> simplefb works for you?
>
> Sorry about that! Yes, it now works.

No worries. Going crazy is part of working on the kernel, I guess.

>> I guess the x86-sysfb patch is still needed?
>
> Yes, that is still needed.

Ok, I will keep watching it then.

>> Now I only wonder why the i915 issue showed up. Is it also solved with
>> a built-in fbcon?
>
> Sadly, no, that problem persists.

I will let Daniel know on IRC.

> A related question: is it expected that simplefb should be
> significantly slower than efifb, or is that something worth looking
> into? My boot with simplefb is roughly five seconds slower than with
> efifb. Coincidentally, I notice the same (or similar slowdown) with
> inteldrmfb when I see the oops (but not otherwise).

That is probably related to the missing write-combine tag in ioremap.
Stephen, any objections to this attached patch?
Tom, if this solves the speed-issues, I will send it out once I get home.

Thanks
David

(Patch also attached in case of new-lines issues)

From dbfb8e12166d494cd60823cbe84134d5d1a73ec8 Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@gmail.com>
Date: Sat, 7 Sep 2013 14:22:01 +0200
Subject: [PATCH] devm/simplefb: introduce and use devm_ioremap_wc()

We want to use devm_ioremap_nocache() or even devm_ioremap_wc() to speed
up fbdev writes _a lot_. As devm_ioremap_wc() doesn't exist, yet,
introduce it along the way. Note that ioremap_wc() is aliases to
ioremap_nocache() in asm-generic/{io,iomem}.h so we can safely expect all
architectures to either provide it or use the same alias.

Reported-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/video/simplefb.c |  4 ++--
 include/linux/io.h       |  2 ++
 lib/devres.c             | 28 ++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/video/simplefb.c b/drivers/video/simplefb.c
index 8d78106..a29f1c4 100644
--- a/drivers/video/simplefb.c
+++ b/drivers/video/simplefb.c
@@ -212,8 +212,8 @@ static int simplefb_probe(struct platform_device *pdev)

  info->fbops = &simplefb_ops;
  info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
- info->screen_base = devm_ioremap(&pdev->dev, info->fix.smem_start,
- info->fix.smem_len);
+ info->screen_base = devm_ioremap_wc(&pdev->dev, info->fix.smem_start,
+    info->fix.smem_len);
  if (!info->screen_base) {
  framebuffer_release(info);
  return -ENODEV;
diff --git a/include/linux/io.h b/include/linux/io.h
index f4f42fa..c529410 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -62,6 +62,8 @@ void __iomem *devm_ioremap(struct device *dev,
resource_size_t offset,
     unsigned long size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
     unsigned long size);
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+      unsigned long size);
 void devm_iounmap(struct device *dev, void __iomem *addr);
 int check_signature(const volatile void __iomem *io_addr,
  const unsigned char *signature, int length);
diff --git a/lib/devres.c b/lib/devres.c
index 8235331..34af7a9 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -72,6 +72,34 @@ void __iomem *devm_ioremap_nocache(struct device
*dev, resource_size_t offset,
 EXPORT_SYMBOL(devm_ioremap_nocache);

 /**
+ * devm_ioremap_wc - Managed ioremap_wc()
+ * @dev: Generic device to remap IO address for
+ * @offset: BUS offset to map
+ * @size: Size of map
+ *
+ * Managed ioremap_wc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+      unsigned long size)
+{
+ void __iomem **ptr, *addr;
+
+ ptr = devres_alloc(devm_ioremap_release, sizeof(*ptr), GFP_KERNEL);
+ if (!ptr)
+ return NULL;
+
+ addr = ioremap_wc(offset, size);
+ if (addr) {
+ *ptr = addr;
+ devres_add(dev, ptr);
+ } else
+ devres_free(ptr);
+
+ return addr;
+}
+EXPORT_SYMBOL(devm_ioremap_wc);
+
+/**
  * devm_iounmap - Managed iounmap()
  * @dev: Generic device to unmap for
  * @addr: Address to unmap
-- 
1.8.4

[-- Attachment #2: 0001-devm-simplefb-introduce-and-use-devm_ioremap_wc.patch --]
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From dbfb8e12166d494cd60823cbe84134d5d1a73ec8 Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@gmail.com>
Date: Sat, 7 Sep 2013 14:22:01 +0200
Subject: [PATCH] devm/simplefb: introduce and use devm_ioremap_wc()

We want to use devm_ioremap_nocache() or even devm_ioremap_wc() to speed
up fbdev writes _a lot_. As devm_ioremap_wc() doesn't exist, yet,
introduce it along the way. Note that ioremap_wc() is aliases to
ioremap_nocache() in asm-generic/{io,iomem}.h so we can safely expect all
architectures to either provide it or use the same alias.

Reported-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/video/simplefb.c |  4 ++--
 include/linux/io.h       |  2 ++
 lib/devres.c             | 28 ++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/video/simplefb.c b/drivers/video/simplefb.c
index 8d78106..a29f1c4 100644
--- a/drivers/video/simplefb.c
+++ b/drivers/video/simplefb.c
@@ -212,8 +212,8 @@ static int simplefb_probe(struct platform_device *pdev)
 
 	info->fbops = &simplefb_ops;
 	info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
-	info->screen_base = devm_ioremap(&pdev->dev, info->fix.smem_start,
-					 info->fix.smem_len);
+	info->screen_base = devm_ioremap_wc(&pdev->dev, info->fix.smem_start,
+					    info->fix.smem_len);
 	if (!info->screen_base) {
 		framebuffer_release(info);
 		return -ENODEV;
diff --git a/include/linux/io.h b/include/linux/io.h
index f4f42fa..c529410 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -62,6 +62,8 @@ void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
 			    unsigned long size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
 				    unsigned long size);
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+			      unsigned long size);
 void devm_iounmap(struct device *dev, void __iomem *addr);
 int check_signature(const volatile void __iomem *io_addr,
 			const unsigned char *signature, int length);
diff --git a/lib/devres.c b/lib/devres.c
index 8235331..34af7a9 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -72,6 +72,34 @@ void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
 EXPORT_SYMBOL(devm_ioremap_nocache);
 
 /**
+ * devm_ioremap_wc - Managed ioremap_wc()
+ * @dev: Generic device to remap IO address for
+ * @offset: BUS offset to map
+ * @size: Size of map
+ *
+ * Managed ioremap_wc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+			      unsigned long size)
+{
+	void __iomem **ptr, *addr;
+
+	ptr = devres_alloc(devm_ioremap_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	addr = ioremap_wc(offset, size);
+	if (addr) {
+		*ptr = addr;
+		devres_add(dev, ptr);
+	} else
+		devres_free(ptr);
+
+	return addr;
+}
+EXPORT_SYMBOL(devm_ioremap_wc);
+
+/**
  * devm_iounmap - Managed iounmap()
  * @dev: Generic device to unmap for
  * @addr: Address to unmap
-- 
1.8.4