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bus: ti-sysc: Flush posted write only after srst_udelay

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commit f71f6ff8c1 upstream.

Commit 34539b442b ("bus: ti-sysc: Flush posted write on enable before
reset") caused a regression reproducable on omap4 duovero where the ISS
target module can produce interconnect errors on boot. Turns out the
registers are not accessible until after a delay for devices needing
a ti,sysc-delay-us value.

Let's fix this by flushing the posted write only after the reset delay.
We do flushing also for ti,sysc-delay-us using devices as that should
trigger an interconnect error if the delay is not properly configured.

Let's also add some comments while at it.

Fixes: 34539b442b ("bus: ti-sysc: Flush posted write on enable before reset")
Cc: stable@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tony Lindgren 2023-11-24 10:50:56 +02:00 committed by Greg Kroah-Hartman
parent d47b2b6a08
commit e4d3534c68
1 changed files with 14 additions and 4 deletions
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16
drivers/bus/ti-sysc.c
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@ -2104,13 +2104,23 @@ static int sysc_reset(struct sysc *ddata)
sysc_val = sysc_read_sysconfig(ddata);
sysc_val |= sysc_mask;
sysc_write(ddata, sysc_offset, sysc_val);
/* Flush posted write */
sysc_val = sysc_read_sysconfig(ddata);
}
/*
* Some devices need a delay before reading registers
* after reset. Presumably a srst_udelay is not needed
* for devices that use a rstctrl register reset.
*/
if (ddata->cfg.srst_udelay)
fsleep(ddata->cfg.srst_udelay);
/*
* Flush posted write. For devices needing srst_udelay
* this should trigger an interconnect error if the
* srst_udelay value is needed but not configured.
*/
sysc_val = sysc_read_sysconfig(ddata);
}
if (ddata->post_reset_quirk)
ddata->post_reset_quirk(ddata);