[U-Boot] [PATCH v2 15/22] x86: ivybridge: Set up an MTRR for the video frame buffer

[Bin Meng]

Hi Simon,

On Sun, Jan 4, 2015 at 11:20 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 3 January 2015 at 20:18, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Simon,
>>
>> On Fri, Jan 2, 2015 at 7:18 AM, Simon Glass <sjg at chromium.org> wrote:
>>> Set the frame buffer to write-combining. This makes it faster, although for
>>> scrolling write-through is even faster for U-Boot.
>>>
>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>> ---
>>>
>>> Changes in v2:
>>> - Remove definition of 'ulong start' from this patch
>>>
>>>  arch/x86/cpu/ivybridge/gma.c | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/arch/x86/cpu/ivybridge/gma.c b/arch/x86/cpu/ivybridge/gma.c
>>> index cf4f87c..6cf9654 100644
>>> --- a/arch/x86/cpu/ivybridge/gma.c
>>> +++ b/arch/x86/cpu/ivybridge/gma.c
>>> @@ -12,6 +12,7 @@
>>>  #include <fdtdec.h>
>>>  #include <pci_rom.h>
>>>  #include <asm/io.h>
>>> +#include <asm/mtrr.h>
>>>  #include <asm/pci.h>
>>>  #include <asm/arch/pch.h>
>>>  #include <asm/arch/sandybridge.h>
>>> @@ -735,6 +736,7 @@ int gma_func0_init(pci_dev_t dev, struct pci_controller *hose,
>>>         ulong start;
>>>  #endif
>>>         void *gtt_bar;
>>> +       ulong base;
>>>         u32 reg32;
>>>         int ret;
>>>
>>> @@ -743,6 +745,11 @@ int gma_func0_init(pci_dev_t dev, struct pci_controller *hose,
>>>         reg32 |= PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY | PCI_COMMAND_IO;
>>>         pci_write_config32(dev, PCI_COMMAND, reg32);
>>>
>>> +       /* Use write-combining for the graphics memory, 256MB */
>>> +       base = pci_read_bar32(hose, dev, 2);
>>> +       mtrr_add_request(MTRR_TYPE_WRCOMB, base, 256 << 20);
>>> +       mtrr_commit(true);
>>> +
>>>         gtt_bar = (void *)pci_read_bar32(pci_bus_to_hose(0), dev, 0);
>>>         debug("GT bar %p\n", gtt_bar);
>>>         ret = gma_pm_init_pre_vbios(gtt_bar);
>>> --
>>
>> Do you have any comments regarding to what I said in
>> http://lists.denx.de/pipermail/u-boot/2014-December/199955.html?
>
> Ah yes I meant to say that I did look at a function to return the BAR
> size, but it involves changing the BAR. I have a patch out to convert
> PCI to driver model and there we will be able to store the size. So
> perhaps we should revisit this later?
>

Sounds good. Let's revisit it later.

Regards,
Bin