[U-Boot] [PATCH 20/22] x86: pci: Allow conditionally run VGA rom in S3

[Bin Meng]

Hi Simon,

On Wed, Mar 22, 2017 at 4:07 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi,
>
> On 16 March 2017 at 08:26, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Introduce a new CONFIG_S3_VGA_ROM_RUN option so that U-Boot can
>> bypass executing VGA roms in S3.
>>
>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>> ---
>>
>>  arch/x86/Kconfig      | 12 ++++++++++++
>>  drivers/pci/pci_rom.c | 14 ++++++++++++++
>>  2 files changed, 26 insertions(+)
>
> Can this be handled at run-time, based on whether we have already run the ROM?
>

I am not sure if this is what you want:

1). If on previous cold boot, VGA ROM has been run. Then on next S3
boot, VGA ROM should also be run.
2). If on previous cold boot, VGA ROM has not been run. Then on next
S3 boot, VGA ROM should not be run.

So this is actually controlled by the CONFIG_VIDEO_VESA driver. But
this new Kconfig option aims to solve: even CONFIG_VIDEO_VESA driver
is used in a normal boot, U-Boot can still bypass the driver probe
(ROM execution) in an S3 boot to save some resume time.

> At present, at least on ivybridge (non-FSP), the ROM execution happens
> when the device comes up. So do we actually need to run the ROM in S3
> Or can we do it later by re-probing the driver?

Regards,
Bin