[U-Boot] U-boot VESA driver Initialization

[vinoth eswaran]

On Tue, Jun 14, 2016 at 11:13 AM, Bin Meng <bmeng.cn at gmail.com> wrote:
> On Tue, Jun 14, 2016 at 2:57 PM, vinoth eswaran <evinoth1206 at gmail.com> wrote:
>> Hello Mr.Bin,
>>
>> On Tue, Jun 14, 2016 at 4:04 AM, Bin Meng <bmeng.cn at gmail.com> wrote:
>>> On Mon, Jun 13, 2016 at 5:41 PM, vinoth eswaran <evinoth1206 at gmail.com> wrote:
>>>> Hello Mr.Bin,
>>>> Hello Mr.George McCollister,
>>>>
>>>>  I am working on an embedded project to optimize Linux boot up time. I have
>>>> a camera application, which I need to run as fast as possible after powering
>>>> up the board.
>>>>
>>>> For this currently I am analyzing how can I optimize the U-boot. As of now,
>>>> u-boot takes around 3 to 4 seconds and most of the time is spent, around 2
>>>> secs in initializing the VESA display.
>>>>
>>>> I have analyzed the sequence of VESA initialization flow and I have
>>>> identified that realmode_call under the function bios_run_on_x86() takes
>>>> more time -- around 1.7 Sec,
>>>>
>>>>     realmode_call(addr + 0x0003, num_dev, 0xffff, 0x0000, 0xffff, 0x0,
>>>>               0x0);
>>>>
>>>> Do you have any idea why this is happening?
>>>>
>>>> I tried removing the VIDEO configuration from u-boot, though the boot up is
>>>> fast , the i915 driver from Linux is reporting an error -- 'i915
>>>> 0000:00:02.0: Invalid ROM contents'
>>>
>>> Can you point out which file in the kernel source that reports this? I
>>> cannot find such message in latest kernel source tree.
>>>
>>      In U-boot I removed the VESA driver support by doing the following changes,
>>
>> In Minnowmax_defconfig:
>> CONFIG_VIDEO_VESA=n
>> CONFIG_FRAMEBUFFER_SET_VESA_MODE=n
>> CONFIG_FRAMEBUFFER_VESA_MODE_11A=n
>>
>> In X86-common.h I commented out the macros defining the VIDEO Configuration,
>>
>> /*
>> #define CONFIG_VIDEO
>> #define CONFIG_VIDEO_SW_CURSOR
>> #define VIDEO_FB_16BPP_WORD_SWAP
>> #define CONFIG_VGA_AS_SINGLE_DEVICE
>> #define CONFIG_CFB_CONSOLE
>> #define CONFIG_CONSOLE_SCROLL_LINES 5
>> */
>>
>> After these changes in the Linux Kernel start up, I am seeing that the
>> i915 driver is not getting properly initialized. I have attached the
>> dmesg logs for your reference.
>>
>> [    0.256735] i915 0000:00:02.0: Invalid ROM contents
>> [    0.262230] [drm] failed to find VBIOS tables
>
> You can try u-boot-x86/pci-working branch, which provides you
> possibility to load the oprom without running. So that you won't see
> "Invalid ROM contents" and "failed to find VBIOS tables" anymore.
>
>>
>> The PCI bus its reporting error corresponds to INTEL VGA controller.
>> 00:02.0 VGA compatible controller: Intel Corporation Atom Processor
>> Z36xxx/Z37xxx Series Graphics & Display (rev 11)
>>
>> The error message is in the Linux source tree:
>> /drivers/pci/rom.c:            dev_err(&pdev->dev, "Invalid ROM contents\n");
>>
>> Though I am seeing i915 init_call  returning 0
>>
>> [    0.720522] initcall i915_init+0x0/0x99 returned 0 after 456068 usecs.
>>
>> I am seeing the weston is not starting up properly. Please let me know
>> if you find any odd behaviour.
>>
>
> What is 'weston'?
    Weston is a display compositor based on wayland protocol. I am
using this to run the camera (Video for Linux - weston client)
application.
For more information you can refer to,
 https://wayland.freedesktop.org/

>>>> I understand that the Linux kernel expects the underlying boot loader to
>>>> setup some initialization which is missing in this case.
>>>>
>>>
>>> My understanding is that if we have native graphics driver in the
>>> kernel, then the bootloader does not need initialize the graphics
>>> hardware.
>>>
>>>> Do you know any methods by which I can speed up the video driver
>>>> initialization phase in u-boot. Please note that I don't need video support
>>>> during u-boot phase,I am not going to use any splash images.
>
> I've tested with the patchset mentioned above, and it looks that the
> Intel i915 driver may still require vbios to be already run. I am not
> familiar with the i915 driver at all, but I am trying to investigate.
>
> Regards,
> Bin