lkml.org 
[lkml]   [2018]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] watchdog: sbsa: use 32-bit read for WCV
On 28.02.18 02:52:20, Jayachandran C wrote:
> According to SBSA spec v3.1 section 5.3:
> All registers are 32 bits in size and should be accessed using
> 32-bit reads and writes. If an access size other than 32 bits
> is used then the results are IMPLEMENTATION DEFINED.
> [...]
> The Generic Watchdog is little-endian
>
> The current code uses readq to read the watchdog compare register
> which does a 64-bit access. This fails on ThunderX2 which does not
> implement 64-bit access to this register.
>
> Fix this by using lo_hi_readq() that does two 32-bit reads.
>
> Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>

Reviewed-by: Robert Richter <rrichter@cavium.com>

I have looked into the non-atomic use of the register access and it
looks sane as the WCV register is only incremented by hardware. There
is no concurrent (write) access from the kernel.

-Robert

\
 
 \ /
  Last update: 2018-03-07 11:05    [W:0.043 / U:29.532 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site