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mtd: rawnand: Ensure nand_soft_waitrdy wait period is enough

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The used way to compute jiffies timeout brokes when
jiffie difference is 1.
Assume that nand_soft_waitrdy is called with timeout_ms==1.
Jiffies are 1000 for example (assume something more like 1000.99
- just before incrementing to 1001).
We compute timeout_ms = 1000+msecs_to_jiffies(1) = 1001.
nand_read_data_op is called for the first time and returns 0.
During the call jiffies changes to 1001 thus "while loop" ends
here (wrongly). Notice that routine was called with expected timeout
1ms but actual timeout used was something between 0...1ms.

Fixes STM32MP1 FMC2 NAND controller which sometimes failed
exactly in this way.

Signed-off-by: Martin Devera <devik@eaxlabs.cz>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200116135431.17480-1-devik@eaxlabs.cz
This commit is contained in:
Martin Devera 2020-01-16 14:54:31 +01:00 committed by Miquel Raynal
parent 98d54f81e3
commit 43d8b63623
1 changed files with 6 additions and 1 deletions
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7
drivers/mtd/nand/raw/nand_base.c
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@ -683,7 +683,12 @@ int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
if (ret)
return ret;
timeout_ms = jiffies + msecs_to_jiffies(timeout_ms);
/*
* +1 below is necessary because if we are now in the last fraction
* of jiffy and msecs_to_jiffies is 1 then we will wait only that
* small jiffy fraction - possibly leading to false timeout
*/
timeout_ms = jiffies + msecs_to_jiffies(timeout_ms) + 1;
do {
ret = nand_read_data_op(chip, &status, sizeof(status), true);
if (ret)