From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: bcm2835: override the HW UART periphid
Date: Tue, 21 May 2013 10:34:17 -0600 [thread overview]
Message-ID: <519BA209.6050407@wwwdotorg.org> (raw)
In-Reply-To: <1369116149-2361-1-git-send-email-neidhard.kim@lge.com>
On 05/21/2013 12:02 AM, Jongsung Kim wrote:
> Stephen Warren reported the recent commit 78506f2 (add support for
> extended FIFO-size of PL011-r1p5) breaks the serial port on the
> BCM2835 ARM SoC.
>
> A UART compatible with the ARM PL011-r1p5 should have 32-deep FIFOs.
> The BCM2835 UART just looks like an ARM PL011-r1p5, but has 16-deep
> FIFOs just like PL011-r1p4 or earlier revisions. As a workaround for
> this compatibility issue, this patch overrides the HW UART periphid
> register values with the actually compatible UART periphid 0x00241011
> (r1p3 or r1p4).
>
> Reported-by: Stephen Warren <swarren@wwwdotorg•org>
> Signed-off-by: Jongsung Kim <neidhard.kim@lge•com>
I know this will work, because I tried out the same thing last week.
However, I'm not convinced that it's the correct approach. What other
changes exist between r1p4 and r1p5; can you check in the TRM? Faking
the periphid would prevent the driver from taking account of any other
changes. Should we instead add a DT property solely to override the FIFO
size, and then set that for bcm2835? I guess if there really aren't any
other SW-visible changes in r1p5, this approach is fine.
next prev parent reply other threads:[~2013-05-21 16:34 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <007301ce375e$bcf6d6b0$36e48410$@lge.com>
2013-05-14 5:56 ` [PATCH] ARM: PL011: add support for extended FIFO-size of PL011-r1p5 Stephen Warren
2013-05-14 7:15 ` Jongsung Kim
2013-05-14 21:03 ` Stephen Warren
2013-05-14 22:50 ` Russell King - ARM Linux
2013-05-15 1:00 ` Jongsung Kim
2013-05-15 4:59 ` Stephen Warren
2013-05-15 9:37 ` Russell King - ARM Linux
2013-05-16 13:26 ` Jongsung Kim
2013-05-21 1:39 ` Jongsung Kim
2013-05-21 2:12 ` Stephen Warren
2013-05-21 6:02 ` [PATCH] ARM: bcm2835: override the HW UART periphid Jongsung Kim
2013-05-21 6:07 ` Jongsung Kim
2013-05-21 9:00 ` Gordon Hollingworth
2013-05-21 16:34 ` Stephen Warren [this message]
2013-05-22 1:43 ` Stephen Warren
2013-05-22 1:52 ` Jongsung Kim
2013-05-30 4:07 Stephen Warren
2013-06-01 6:43 ` Olof Johansson
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