[PATCH v4] mtd: rawnand: hynix: fix up bit 0 of sdr_timing_mode

[Hector Palacios]

Hi Miquèl,

On 3/8/23 16:38, Miquel Raynal wrote:
> [EXTERNAL E-MAIL] Warning! This email originated outside of the organization! Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> 
> 
> Hi Hector,
> 
> hector.palacios at digi.com wrote on Wed,  8 Mar 2023 15:29:26 +0100:
> 
>> According to the ONFI specification, bit 0 of 'SDR timing mode support'
>> (bytes 129-130) "shall be 1". That means the NAND supports at least
>> timing mode 0.
>>
>> NAND chip Hynix H27U4G8F2GDA-BI (at least) is reading a 0 on this field
>> which makes nand_choose_best_sdr_timings() return with error and the
>> probe function to eventually fail.
>>
>> Given that sdr_timing_modes bit 0 must be 1 by specification, force
>> it in case the NAND reports it is not set. This is a safe assumption
>> because the mode 0 is the minimum (safer) set of timings that the
>> NAND can work with.
>>
>> Signed-off-by: Hector Palacios <hector.palacios at digi.com>
>> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
>> Link: https://linkprotect.cudasvc.com/url?a=https%3a%2f%2flore.kernel.org%2flinux-mtd%2f20230223165104.525852-1-hector.palacios%40digi.com&c=E,1,RLpgBTfrKosVog1g_fhQAfX087I9gUEu_fXTw6WsUNm-G6Vo7RyUNXJHK4fLNCL8YR0nigdEto-n8SGD5uoEffwtebOXZyc6IZTKoiWXVp38s56Gh8eZrjhf7g_L&typo=1
>> ---
>> v4:
>>    Fix bitwise operation on __le16 type, per sparse warning.
> 
> Sorry I had no time to answer your question, see below.
> 
>> v3:
>>    Forcibly set bit 0.
>> v2:
>>    Move patch to Hynix specific fixup hook.
>>    Use BIT(0) macro.
>> v1:
>>    Implement generic patch in nand_base.c.
>>
>>
>>   drivers/mtd/nand/raw/nand_hynix.c | 13 +++++++++++++
>>   1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/raw/nand_hynix.c b/drivers/mtd/nand/raw/nand_hynix.c
>> index 0d4d4bbfdece..c17cca316148 100644
>> --- a/drivers/mtd/nand/raw/nand_hynix.c
>> +++ b/drivers/mtd/nand/raw/nand_hynix.c
>> @@ -728,8 +728,21 @@ static int hynix_nand_init(struct nand_chip *chip)
>>        return ret;
>>   }
>>
>> +static void hynix_fixup_onfi_param_page(struct nand_chip *chip,
>> +                                     struct nand_onfi_params *p)
>> +{
>> +     /*
>> +      * Certain chips might report a 0 on sdr_timing_mode field
>> +      * (bytes 129-130). This has been seen on H27U4G8F2GDA-BI.
>> +      * According to ONFI specification, bit 0 of this field "shall be 1".
>> +      * Forcibly set this bit.
>> +      */
>> +     p->sdr_timing_modes = cpu_to_le16(le16_to_cpu(p->sdr_timing_modes) | BIT(0));
> 
> Why not just:
> 
>          p->sdr_timing_modes |= cpu_to_le16(BIT(0));

Sigh. I'd swear I tried this and sparse still complained, but you're 
right. This is fine. I'll resubmit. Thanks.

> 
> ?
> 
>> +}
>> +
>>   const struct nand_manufacturer_ops hynix_nand_manuf_ops = {
>>        .detect = hynix_nand_decode_id,
>>        .init = hynix_nand_init,
>>        .cleanup = hynix_nand_cleanup,
>> +     .fixup_onfi_param_page = hynix_fixup_onfi_param_page,
>>   };
> 
> 
> Thanks,
> Miquèl
-- 
Héctor Palacios