Re: [PATCH v4 2/3] mtd: cfi_cmdset_0002: Use chip_ready() for write on S29GL064N

[Tokunori Ikegami <ikegami.t@gmail.com>]

Hi Miquèl-san,

On 2022/03/17 2:21, Miquel Raynal wrote:
> Hi Tokunori,
>
> ikegami.t@gmail.com wrote on Thu, 17 Mar 2022 00:54:54 +0900:
>
>> As pointed out by this bug report [1], buffered writes are now broken on
>> S29GL064N. This issue comes from a rework which switched from using chip_good()
>> to chip_ready(), because DQ true data 0xFF is read on S29GL064N and an error
>> returned by chip_good().
> Vignesh, I believe you understand this issue better than I do, can you
> propose an improved commit log?
>
>> One way to solve the issue is to revert the change
>> partially to use chip_ready for S29GL064N.
>>
>> [1] https://lore.kernel.org/r/b687c259-6413-26c9-d4c9-b3afa69ea124@pengutronix.de/
>>
>> Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
>> Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>
>> Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> Cc: stable@vger.kernel.org
>> ---
>>   drivers/mtd/chips/cfi_cmdset_0002.c | 25 +++++++++++++++++++++----
>>   1 file changed, 21 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
>> index e68ddf0f7fc0..6c57f85e1b8e 100644
>> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
>> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
>> @@ -866,6 +866,23 @@ static int __xipram chip_check(struct map_info *map, struct flchip *chip,
>>   		chip_check(map, chip, addr, &datum); \
>>   	})
>>   
>> +static bool __xipram cfi_use_chip_ready_for_write(struct map_info *map)
> At the very least I would call this function:
> cfi_use_chip_ready_for_writes()
>
> Yet, I still don't fully get what chip_ready is versus chip_good.
This was deleted as to use the quirks flag instead.
>
>> +{
>> +	struct cfi_private *cfi = map->fldrv_priv;
>> +
>> +	return cfi->mfr == CFI_MFR_AMD && cfi->id == 0x0c01;
>> +}
>> +
>> +static int __xipram chip_good_for_write(struct map_info *map,
>> +					struct flchip *chip, unsigned long addr,
>> +					map_word expected)
>> +{
>> +	if (cfi_use_chip_ready_for_write(map))
>> +		return chip_ready(map, chip, addr);
> If possible and not too invasive I would definitely add a "quirks" flag
> somewhere instead of this cfi_use_chip_ready_for_write() check.
Added the quirks flag by the version 5 patch.
>
> Anyway, I would move this to the chip_good() implementation directly so
> we partially hide the quirks complexity from the core.

Yes also added the chip_good to check the quirks flag.

Regards,
Ikegami

>
>> +
>> +	return chip_good(map, chip, addr, expected);
>> +}
>> +
>>   static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
>>   {
>>   	DECLARE_WAITQUEUE(wait, current);
>> @@ -1686,7 +1703,7 @@ static int __xipram do_write_oneword_once(struct map_info *map,
>>   		 * "chip_good" to avoid the failure due to scheduling.
>>   		 */
>>   		if (time_after(jiffies, timeo) &&
>> -		    !chip_good(map, chip, adr, datum)) {
>> +		    !chip_good_for_write(map, chip, adr, datum)) {
>>   			xip_enable(map, chip, adr);
>>   			printk(KERN_WARNING "MTD %s(): software timeout\n", __func__);
>>   			xip_disable(map, chip, adr);
>> @@ -1694,7 +1711,7 @@ static int __xipram do_write_oneword_once(struct map_info *map,
>>   			break;
>>   		}
>>   
>> -		if (chip_good(map, chip, adr, datum)) {
>> +		if (chip_good_for_write(map, chip, adr, datum)) {
>>   			if (cfi_check_err_status(map, chip, adr))
>>   				ret = -EIO;
>>   			break;
>> @@ -1966,14 +1983,14 @@ static int __xipram do_write_buffer_wait(struct map_info *map,
>>   		 * "chip_good" to avoid the failure due to scheduling.
>>   		 */
>>   		if (time_after(jiffies, timeo) &&
>> -		    !chip_good(map, chip, adr, datum)) {
>> +		    !chip_good_for_write(map, chip, adr, datum)) {
>>   			pr_err("MTD %s(): software timeout, address:0x%.8lx.\n",
>>   			       __func__, adr);
>>   			ret = -EIO;
>>   			break;
>>   		}
>>   
>> -		if (chip_good(map, chip, adr, datum)) {
>> +		if (chip_good_for_write(map, chip, adr, datum)) {
>>   			if (cfi_check_err_status(map, chip, adr))
>>   				ret = -EIO;
>>   			break;
>
> Thanks,
> Miquèl