linux-kernel - Re: [PATCH v2 06/12] mtd: rawnand: stm32_fmc2: use FMC2_TIMEOUT

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Message-ID: <0e2c9a6a-aa21-7814-9af8-629de6568fab@st.com>
Date:   Wed, 29 Apr 2020 11:27:43 +0200
From:   Christophe Kerello <christophe.kerello@...com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
CC:     <richard@....at>, <vigneshr@...com>, <lee.jones@...aro.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>, <tony@...mide.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <devicetree@...r.kernel.org>, <marex@...x.de>
Subject: Re: [PATCH v2 06/12] mtd: rawnand: stm32_fmc2: use FMC2_TIMEOUT_MS
 for timeouts

Hi Miquèl,

On 4/27/20 8:22 PM, Miquel Raynal wrote:
> Hi Christophe,
> 
> Christophe Kerello <christophe.kerello@...com> 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@...com>
>> ---
>>   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,
> Miquèl
> 

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.

Regards,
Christophe Kerello.