Re: [PATCH v2 06/12] mtd: rawnand: stm32_fmc2: use FMC2_TIMEOUT_MS for timeouts

[Christophe Kerello]

On 4/29/20 11:35 AM, Miquel Raynal wrote:
> Hi Christophe,
>
> Christophe Kerello <christophe.kerello@xxxxxx> wrote on Wed, 29 Apr
> 2020 11:27:43 +0200:
>
> > Hi MiquÃl,
> >
> > On 4/27/20 8:22 PM, Miquel Raynal wrote:
> > > Hi Christophe,
> > >
> > > Christophe Kerello <christophe.kerello@xxxxxx> wrote on Wed, 15 Apr
> > > 2020 17:57:30 +0200:
> > >    
> > > > This patch removes the constant FMC2_TIMEOUT_US.
> > > > FMC2_TIMEOUT_MS is set to 5 seconds and this constant is used
> > > > each time that we need to wait (except when the timeout value
> > > > is set by the framework)
> > > >
> > > > Signed-off-by: Christophe Kerello <christophe.kerello@xxxxxx>
> > > > ---
> > > >    drivers/mtd/nand/raw/stm32_fmc2_nand.c | 11 +++++------
> > > >    1 file changed, 5 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/mtd/nand/raw/stm32_fmc2_nand.c b/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> > > > index ab53314..f159c39 100644
> > > > --- a/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> > > > +++ b/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> > > > @@ -37,8 +37,7 @@
> > > >    /* Max ECC buffer length */
> > > >    #define FMC2_MAX_ECC_BUF_LEN		(FMC2_BCHDSRS_LEN * FMC2_MAX_SG)
> > > >    >> -#define FMC2_TIMEOUT_US			1000
> > > > -#define FMC2_TIMEOUT_MS			1000
> > > > +#define FMC2_TIMEOUT_MS			5000
> > > >    >>   /* Timings */
> > > >    #define FMC2_THIZ			1
> > > > @@ -525,9 +524,9 @@ static int stm32_fmc2_ham_calculate(struct nand_chip *chip, const u8 *data,
> > > >    	u32 sr, heccr;
> > > >    	int ret;
> > > >    >> -	ret = readl_relaxed_poll_timeout(fmc2->io_base + FMC2_SR,
> > > > -					 sr, sr & FMC2_SR_NWRF, 10,
> > > > -					 FMC2_TIMEOUT_MS);
> > > > +	ret = readl_relaxed_poll_timeout_atomic(fmc2->io_base + FMC2_SR,
> > > > +						sr, sr & FMC2_SR_NWRF, 1,
> > > > +						1000 * FMC2_TIMEOUT_MS);
> > >
> > > Is the _atomic suffix needed here? If yes it would deserve a separate
> > > patch with Fixes/Stable tags.
> > >    
> >
> > I have currently not seen any issues. So, I will remove this modification as we will move to regmap_read_poll_timeout in patch 10.
> >
> > > >    	if (ret) {
> > > >    		dev_err(fmc2->dev, "ham timeout\n");
> > > >    		return ret;
> > > > @@ -1315,7 +1314,7 @@ static int stm32_fmc2_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
> > > >    	/* Check if there is no pending requests to the NAND flash */
> > > >    	if (readl_relaxed_poll_timeout_atomic(fmc2->io_base + FMC2_SR, sr,
> > > >    					      sr & FMC2_SR_NWRF, 1,
> > > > -					      FMC2_TIMEOUT_US))
> > > > +					      1000 * FMC2_TIMEOUT_MS))
> > > >    		dev_warn(fmc2->dev, "Waitrdy timeout\n");
> > > >    >>   	/* Wait tWB before R/B# signal is low */
> > >
> > > You change the timeouts from 1ms to 5s.
> > >
> > > Maybe 5s is a little bit too much IMHO but we don't really care as this
> > > is a timeout. However 1ms is tight. If you are changing this value
> > > because it triggers error (eg. when the machine is loaded), then it is
> > > a fix and should appear like it.
> > >
> > > Thanks,
> > > MiquÃl
> > >    
> >
> > No errors currently happens.
> > During our stress tests, in a overloaded system, we have seen that we could be close to 1 second, even if we never met this value.
> > So, to be safe, I have set this timeout to 5 seconds.
> > As it is just a timeout value, I have not seen any side effect.
> > I am using the same timeout constant to avoid to have one timeout per cases.
>
> Something is wrong in my mind:
> You say you observe delays of almost up to 1 second, but the polling
> currently happens on 1000 us = 1ms, either you had timeouts or I
> misread something?
>
> Thanks,
> MiquÃl

Hi MiquÃl,

My fault. For this polling, we never met 1 ms.
The 1 second observed was on the sequencer when we read/write a page (as 
it the same timeout value that is used)

Regards,
Christophe Kerello.