[PATCH] mtd: rawnand: gpmi: Fix setting busy timeout setting

[Greg KH]

On Fri, Jul 15, 2022 at 07:22:09AM -0700, Guenter Roeck wrote:
> On Tue, Jun 14, 2022 at 10:31:38AM +0200, Sascha Hauer wrote:
> > The DEVICE_BUSY_TIMEOUT value is described in the Reference Manual as:
> > 
> > | Timeout waiting for NAND Ready/Busy or ATA IRQ. Used in WAIT_FOR_READY
> > | mode. This value is the number of GPMI_CLK cycles multiplied by 4096.
> > 
> > So instead of multiplying the value in cycles with 4096, we have to
> > divide it by that value. Use DIV_ROUND_UP to make sure we are on the
> > safe side, especially when the calculated value in cycles is smaller
> > than 4096 as typically the case.
> > 
> > This bug likely never triggered because any timeout != 0 usually will
> > do. In my case the busy timeout in cycles was originally calculated as
> > 2408, which multiplied with 4096 is 0x968000. The lower 16 bits were
> > taken for the 16 bit wide register field, so the register value was
> > 0x8000. With 2970bf5a32f0 ("mtd: rawnand: gpmi: fix controller timings
> > setting") however the value in cycles became 2384, which multiplied
> > with 4096 is 0x950000. The lower 16 bit are 0x0 now resulting in an
> > intermediate timeout when reading from NAND.
> > 
> > Fixes: b1206122069aa ("mtd: rawnand: gpmi: use core timings instead of an empirical derivation")
> > Cc: stable at vger.kernel.org
> > Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> 
> I see this patch was reverted in a set of rush stable releases,
> but I still see it in the mainline kernel. Is it going to be reverted
> there as well ?

A fix has been sent, it was said to be picked up hopefully next week:
	https://lore.kernel.org/all/20220701110341.3094023-1-s.hauer@pengutronix.de/

thanks,

greg k-h