[PATCH 3/3] alpha, drm: Add Alpha support to Radeon DRM code

[PATCH 3/3] alpha, drm: Add Alpha support to Radeon DRM code

[Jay Estabrook]

Alpha needs to have the system bus address for the device's local
memory available, so that it can be returned to user-level, where
it may be used in an mmap(). So, we make bus.addr hold the ioremap()
return for kernel use, and then we can modify bus.base appropriately.

Signed-off-by: Jay Estabrook <jay.estabrook@gmail.com>
---
 drivers/gpu/drm/radeon/radeon_ttm.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff -Naurp a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
--- a/drivers/gpu/drm/radeon/radeon_ttm.c	2011-04-26 23:48:50.000000000 -0400
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c	2011-05-03 18:24:27.000000000 -0400
@@ -450,6 +450,29 @@ static int radeon_ttm_io_mem_reserve(str
 			return -EINVAL;
 		mem->bus.base = rdev->mc.aper_base;
 		mem->bus.is_iomem = true;
+#ifdef __alpha__
+		/*
+		 * Alpha: use bus.addr to hold the ioremap() return,
+		 * so we can modify bus.base below.
+		 */
+		if (mem->placement & TTM_PL_FLAG_WC)
+			mem->bus.addr =
+				ioremap_wc(mem->bus.base + mem->bus.offset,
+					   mem->bus.size);
+		else
+			mem->bus.addr =
+				ioremap_nocache(mem->bus.base + mem->bus.offset,
+						mem->bus.size);
+
+		/*
+		 * Alpha: Take just the bus offset and
+		 * add the hose/domain memory base.
+		 * Then, bus.base can be returned
+		 * for use in an mmap() call.
+		 */
+		mem->bus.base = (mem->bus.base & 0x0ffffffffUL) +
+			rdev->ddev->hose->dense_mem_base;
+#endif
 		break;
 	default:
 		return -EINVAL;

---

Re: [PATCH 3/3] alpha, drm: Add Alpha support to Radeon DRM code

[Dave Airlie]

On Fri, Jun 10, 2011 at 8:20 AM, Jay Estabrook <jay.estabrook@gmail.com> wrote:
>
> Alpha needs to have the system bus address for the device's local
> memory available, so that it can be returned to user-level, where
> it may be used in an mmap(). So, we make bus.addr hold the ioremap()
> return for kernel use, and then we can modify bus.base appropriately.
>

I don't get this. why is mmap passing in an address? we don't do that anymore.

When you mmap the device node it passes back a hashed offset in the
table, that the
kernel then translates into a proper address and sets up the page tables.

So I really don't get what this patch is doing, either the
explaination of what it is doing is wrong
or it is wrong.

Dave.

Re: [PATCH 3/3] alpha, drm: Add Alpha support to Radeon DRM code

[Jay Estabrook]

Hi, Dave,

It is the explanation that is inaccurate; I was still thinking about mmap when
the new paradigm is to do the mapping when the VM faults.

I believe the code that requires this patch is: ttm/ttm_bo_vm.c: ttm_bo_vm_fault(),
specifically:

    for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
        if (bo->mem.bus.is_iomem)
            pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset;
        else {

The "pfn" needs to reflect the correct system bus address to get to the VRAM
on the graphics card.

I will rework the commentary and resend.

Thanks for the feedback.

Jay


On 06/13/2011 07:35 PM, Dave Airlie wrote:
> On Fri, Jun 10, 2011 at 8:20 AM, Jay Estabrook <jay.estabrook@gmail.com> wrote:
>> Alpha needs to have the system bus address for the device's local
>> memory available, so that it can be returned to user-level, where
>> it may be used in an mmap(). So, we make bus.addr hold the ioremap()
>> return for kernel use, and then we can modify bus.base appropriately.
>>
> 
> I don't get this. why is mmap passing in an address? we don't do that anymore.
> 
> When you mmap the device node it passes back a hashed offset in the
> table, that the
> kernel then translates into a proper address and sets up the page tables.
> 
> So I really don't get what this patch is doing, either the
> explaination of what it is doing is wrong
> or it is wrong.
> 
> Dave.