From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrea Baldini <andrea.baldini@spesonline.com>
Date: Tue, 22 Nov 2011 13:15:22 +0000
Subject: SH2a Write-back cache issue
Message-Id: <201111221415.22367.andrea.baldini@spesonline.com>
List-Id: <linux-sh.vger.kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: linux-sh@vger.kernel.org

Hi,

I'm working on a sh7203 board and I'm currently using a 2.6.28 kernel with a 
write-back cache mode configuration.
When this configuration is set I got some issues when the flush_icache_range is 
involved.

/* O-Cache writeback */
for (way = 0; way < 4; way++) {
unsigned long data =  ctrl_inl(CACHE_OC_ADDRESS_ARRAY | addr | (way << 11));
	if ((data & CACHE_PHYSADDR_MASK) = (v & CACHE_PHYSADDR_MASK)) {
		data &= ~SH_CACHE_UPDATED;
		ctrl_outl(data, CACHE_OC_ADDRESS_ARRAY | addr | (way << 11));
	}
}

When the O-cache writeback is performed all system interrupts are missed, 
including the timer one.
This occurs, for instance, when a flat binary is loaded in memory ( 
load_flat_file() ) or when a signal is handled ( when setting up a frame ).

This is an unacceptable behaviour for the system. 
A workaround is setting a write-through configuration to the kernel and flushing 
just the instruction cache entries.

I've seen the recent kernel releases but it seems this part hasn't been 
modified yet.
Anyway i tried a 2.6.35 kernel version some time ago and i got the same 
problems.

Is anybody here working on this issue?
Is it possible to use the write-back configuration?

Regards

Andrea