[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <97639381-2558-4cf5-75b0-7f80f0393b16@gmail.com>
Date: Fri, 23 Dec 2022 16:58:30 +0200
From: Markuss Broks <markuss.broks@...il.com>
To: Ard Biesheuvel <ardb@...nel.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
Jami Kettunen <jami.kettunen@...tonmail.com>,
Jonathan Corbet <corbet@....net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>,
Helge Deller <deller@....de>, Borislav Petkov <bp@...e.de>,
"Paul E. McKenney" <paulmck@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Will Deacon <will@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
Muchun Song <muchun.song@...ux.dev>,
Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
Kim Phillips <kim.phillips@....com>, linux-doc@...r.kernel.org,
linux-efi@...r.kernel.org, linux-serial@...r.kernel.org,
linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v3 0/3] Add generic framebuffer support to EFI earlycon
driver
Hi Ard,
On 12/23/22 16:42, Ard Biesheuvel wrote:
> (cc Andy)
>
>
> On Wed, 21 Dec 2022 at 11:54, Markuss Broks <markuss.broks@...il.com> wrote:
>> Make the EFI earlycon driver be suitable for any linear framebuffers.
>> This should be helpful for early porting of boards with no other means of
>> output, like smartphones/tablets. There seems to be an issue with early_ioremap
>> function on ARM32, but I am unable to find the exact cause. It appears the mappings
>> returned by it are somehow incorrect, thus the driver is disabled on ARM.
> The reason that this driver is disabled on ARM is because the struct
> screen_info is not populated early enough, as it is retrieved from a
> UEFI configuration table.
I believe I must be hitting some other bug then, since my driver should
not use `struct screen_info` when the arguments are specified manually
(e.g. in device-tree or in kernel command line options), and it still is
broken on ARM when they are. I got it to work on ARM when I moved the
early console initialization later into the kernel booting process, but
that mostly defeats the purpose of early console driver, I believe. I've
been thinking that it could be some stuff not getting initialized early
enough indeed, but I've got no clue what could it be.
>
> early_ioremap() works fine on ARM as long as they mapping is torn down
> before paging_init()
>
>> EFI early
>> console was disabled on IA64 previously because of missing early_memremap_prot,
>> and this is inherited to this driver.
>>
>> This patch also changes
> "This patch also changes ..." is usually a strong hint to self that
> the patches need to be split up.
>
>> behavior on EFI systems, by selecting the mapping type
>> based on if the framebuffer region intersects with system RAM. If it does, it's
>> common sense that it should be in RAM as a whole, and so the system RAM mapping is
>> used. It was tested to be working on my PC (Intel Z490 platform), as well as several
>> ARM64 boards (Samsung Galaxy S9 (Exynos), iPad Air 2, Xiaomi Mi Pad 4, ...).
>>
>> Markuss Broks (2):
>> drivers: serial: earlycon: Pass device-tree node
>> efi: earlycon: Add support for generic framebuffers and move to fbdev
>> subsystem
>>
>>
>> v1 -> v2:
>>
>> - a new patch correcting serial/earlycon.c argument name to "offset" instead
>> of "node"
>> - move IA64 exclusion from EFI earlycon Kconfig to earlycon driver Kconfig
>> (IA64 has no early_memremap_prot)
>> - move driver from fbdev to console subsystem
>> - select EFI earlycon by default
>> - fetch stride manually from device-tree, as on some devices it seems stride
>> doesn't match the horizontal resolution * bpp.
>> - use saner format (e.g. 1920x1080x32 instead of 1920,1080,32).
>>
>>
>> Markuss Broks (3):
>> drivers: serial: earlycon: Pass device-tree node
>> efi: earlycon: move to video/console to prepare for changes
>> efi: earlycon: Add support for generic framebuffers
>>
>> .../admin-guide/kernel-parameters.txt | 12 +-
>> MAINTAINERS | 5 +
>> drivers/firmware/efi/Kconfig | 7 +-
>> drivers/firmware/efi/Makefile | 1 -
>> drivers/firmware/efi/earlycon.c | 246 --------------
>> drivers/tty/serial/earlycon.c | 3 +
>> drivers/video/console/Kconfig | 11 +
>> drivers/video/console/Makefile | 1 +
>> drivers/video/console/earlycon.c | 305 ++++++++++++++++++
>> include/linux/serial_core.h | 1 +
>> 10 files changed, 336 insertions(+), 256 deletions(-)
>> delete mode 100644 drivers/firmware/efi/earlycon.c
>> create mode 100644 drivers/video/console/earlycon.c
>>
>> --
>> 2.39.0
>>
- Markuss
P.S. Just noticed I forgot to Ctrl^S the cover letter before saving...
The main change v3 does is separate the moving action and edit action
into two separate commits, I don't think there're more major changes.
With v4 I'd try to attach the proper version log.
Powered by blists - more mailing lists