Re: [RFC PATCH] efi/fb: Convert PCI bus address to resource if translated by the bridge

2018-05-18 Thread Sinan Kaya
On 5/17/2018 6:17 AM, Robin Murphy wrote:
>> +    }
>> +
> 
> Is this not pretty much just pcibios_bus_to_resource()?
>

Agreed, let me convert the code to use pcibios_bus_to_resource() API.
I wasn't aware of its existence.
 
> Robin.


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Re: [RFC PATCH] efi/fb: Convert PCI bus address to resource if translated by the bridge

2018-05-17 Thread Robin Murphy

On 16/05/18 19:23, Sinan Kaya wrote:

A host bridge is allowed to remap BAR addresses using _TRA attribute in
_CRS windows.

pci_bus :00: root bus resource [mem 0x8010010-0x8011fff window] 
(bus address [0x0010-0x1fff])
pci :02:00.0: reg 0x10: [mem 0x8011e00-0x8011eff]

When a VGA device is behind such a host bridge and the resource is
translated efifb driver is trying to do ioremap against bus address
rather than the resource address and is failing to probe.

efifb driver is having difficulty locating the base address from BAR
address when

efifb: probing for efifb
efifb: cannot reserve video memory at 0x1e00
efifb: framebuffer at 0x1e00, using 1920k, total 1875k
efifb: mode is 800x600x32, linelength=3200, pages=1
efifb: scrolling: redraw
efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0

Use the host bridge offset information to convert bus address to
resource address in the fixup.

Signed-off-by: Sinan Kaya 
---
  drivers/video/fbdev/efifb.c | 23 +++
  1 file changed, 23 insertions(+)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index 46a4484..feef02b 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -428,6 +428,8 @@ static void efifb_fixup_resources(struct pci_dev *dev)
  {
u64 base = screen_info.lfb_base;
u64 size = screen_info.lfb_size;
+   struct pci_host_bridge *bridge;
+   struct resource_entry *window;
int i;
  
  	if (efifb_pci_dev || screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)

@@ -439,6 +441,27 @@ static void efifb_fixup_resources(struct pci_dev *dev)
if (!base)
return;
  
+	bridge = pci_find_host_bridge(dev->bus);

+   if (!bridge)
+   return;
+
+   resource_list_for_each_entry(window, &bridge->windows) {
+   phys_addr_t win_start;
+   phys_addr_t win_end;
+   size_t win_size;
+
+   if (resource_type(window->res) != IORESOURCE_MEM)
+   continue;
+
+   win_start = window->res->start - window->offset;
+   win_end = window->res->end - window->offset;
+   win_size = window->res->end - window->res->start + 1;
+   if (win_start <= base && win_end >= base + win_size - 1) {
+   base += window->offset;
+   break;
+   }
+   }
+


Is this not pretty much just pcibios_bus_to_resource()?

Robin.


for (i = 0; i <= PCI_STD_RESOURCE_END; i++) {
struct resource *res = &dev->resource[i];
  


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Re: [RFC PATCH] efi/fb: Convert PCI bus address to resource if translated by the bridge

2018-05-17 Thread Sinan Kaya
On 5/16/2018 2:31 PM, Timur Tabi wrote:
> On 05/16/2018 01:23 PM, Sinan Kaya wrote:
>> +    win_start = window->res->start - window->offset;
> 
> Can you guarantee that window->res->start is always >= window->offset?
> 

Resource offset is generally 0 when not translating or a positive number
that you subtract from the resource start to reach to the translating window.

Having a bigger offset than resource start should be considered a BIOS bug.

>> +    win_size = window->res->end - window->res->start + 1;
> 
> Use resource_size() instead.
> 

I'll fix it.

-- 
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Re: [RFC PATCH] efi/fb: Convert PCI bus address to resource if translated by the bridge

2018-05-17 Thread Timur Tabi

On 05/16/2018 01:23 PM, Sinan Kaya wrote:

+   win_start = window->res->start - window->offset;


Can you guarantee that window->res->start is always >= window->offset?


+   win_size = window->res->end - window->res->start + 1;


Use resource_size() instead.

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Re: [RFC PATCH] efi/fb: Convert PCI bus address to resource if translated by the bridge

2018-05-17 Thread Sinan Kaya
On 5/16/2018 2:23 PM, Sinan Kaya wrote:
> + if (win_start <= base && win_end >= base + win_size - 1) {
> + base += window->offset;
> + break;
> + }

I should probably add window->offset!=0 to the if statement in order not to
break non-translating case.

Any other comments?

-- 
Sinan Kaya
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Technologies, Inc.
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Foundation Collaborative Project.
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