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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Sven Anderson <sven@anderson.de>
Cc: Matthias Lange <matthias.lange@kernkonzept.com>,
	The development of GNU GRUB <grub-devel@gnu.org>
Subject: Re: [PATCH 3/5] ns8250: Add base support for MMIO UARTs
Date: Wed, 31 Aug 2022 15:56:05 +1000	[thread overview]
Message-ID: <d3678aae43df7d0e4e7393dbb4e7c25d0adb7cfa.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAAQhRycnu8WyieWZ8uGT7T+in_s9rASQndRtCMhkMnOibPqKOQ@mail.gmail.com>

On Mon, 2022-05-23 at 19:11 +0200, Sven Anderson wrote:
> 
> I had a couple of sleepless nights trying to find out why this didn't
> work for my MMIO UART (Intel Cannon Lake PCH Intel C246), so I
> thought I would share my findings with others in a similar situation.
> (See below.)
>  
 .../...
> 
> This code assumes that the registers are only 8 bit wide. Apparently
> for my chipset they are 32 bits wide, so it only (finally) worked
> when I rewrote this code to address and write full grub_uint32_t
> values, like this: 
> 
> ------
>   volatile grub_uint32_t* p = (void*)(port->mmio_base);
>   *(p + reg) = (grub_uint32_t)(value);
> ------

Sorry, I dopped the ball on this for a while. Getting back to it and
will re-submit the patches.

Can you send me a dump of your SPCR table ? I'd like to see if it
properly says "32-bit" there to auto-detect this.

Cheers,
Ben.


  parent reply	other threads:[~2022-08-31  5:58 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 22:07 [PATCH 0/5] serial: Add MMIO & SPCR support for AWS EC2 metal instances Benjamin Herrenschmidt
2021-03-18 22:07 ` [PATCH 1/5] acpi: Export a generic grub_acpi_find_table Benjamin Herrenschmidt
2021-03-18 22:07 ` [PATCH 2/5] acpi: Add SPCR and generic address definitions Benjamin Herrenschmidt
2021-03-18 22:07 ` [PATCH 3/5] ns8250: Add base support for MMIO UARTs Benjamin Herrenschmidt
2021-03-19 17:16   ` Glenn Washburn
2021-03-19 23:30     ` Benjamin Herrenschmidt
2022-05-23 17:11   ` Sven Anderson
2022-05-25  3:13     ` Benjamin Herrenschmidt
2022-08-31  5:56     ` Benjamin Herrenschmidt [this message]
2022-08-31  8:26       ` Benjamin Herrenschmidt
2022-09-02  3:58         ` Benjamin Herrenschmidt
2021-03-18 22:07 ` [PATCH 4/5] ns8250: Add configuration parameter when adding ports Benjamin Herrenschmidt
2021-03-18 22:07 ` [PATCH 5/5] ns8250: Use ACPI SPCR table when available to configure serial Benjamin Herrenschmidt
2021-03-19  0:03 ` [PATCH 0/5] serial: Add MMIO & SPCR support for AWS EC2 metal instances Glenn Washburn
2021-03-19  1:27   ` Benjamin Herrenschmidt
2021-03-19 16:25     ` Glenn Washburn
2021-03-23 18:04 ` Daniel Kiper
2021-03-23 22:23   ` Benjamin Herrenschmidt

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