linux-kernel - Re: [PATCH v2] mtd: micron-st: enable lock/unlock for mt25qu512a

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Date:   Fri, 6 Oct 2023 16:09:47 +0000
From:   SHUKLA Mamta Ramendra <mamta.shukla@...ca-geosystems.com>
To:     Tudor Ambarus <tudor.ambarus@...aro.org>,
        "pratyush@...nel.org" <pratyush@...nel.org>,
        "michael@...le.cc" <michael@...le.cc>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        "richard@....at" <richard@....at>,
        "vigneshr@...com" <vigneshr@...com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     GEO-CHHER-bsp-development 
        <bsp-development.geo@...ca-geosystems.com>
Subject: Re: [PATCH v2] mtd: micron-st: enable lock/unlock for mt25qu512a



Hello Tudor,


> On 10/6/23 14:33, Tudor Ambarus wrote:
>>
>> Hi,
>>
>> Thanks for the debugging info.
>>
>> On 10/6/23 11:30, SHUKLA Mamta Ramendra wrote:
>>
>> cut
>>
>>> --------------------------------------------------------
>>>
>>> IMO, HAS_16BIT_SR flag is causing lock/unlock failure,
>>> since BP bits are calculated wrong then.
>>>
>>> I tested also for a case where I don't parse SFDP and
>>> reverted the condition in  micron_st_nor_default_init()
>>> for 16BIT Status Register Flag. And lock/unlock fails with
>>> same log as Non-working case.
>>>
>>> And this mt25qu512 has 8-BIT SR as typical micron-st flash.
>>>
>>
>> Indeed, the problem is that HAS_16BIT_SR gets set when it shouldn't have
>> to. This means that the BFPT table of the flash is wrong and we should
>> fix the parsed settings via a post_bfpt hook.
>>
>> Does the following fix your problem?
>>
> 
> here it is again, this time compile tested:
> 
> diff --git a/drivers/mtd/spi-nor/micron-st.c
> b/drivers/mtd/spi-nor/micron-st.c
> index 4afcfc57c896..20f76e278095 100644
> --- a/drivers/mtd/spi-nor/micron-st.c
> +++ b/drivers/mtd/spi-nor/micron-st.c
> @@ -180,6 +180,18 @@ static const struct flash_info micron_nor_parts[] = {
>          },
>   };
> 
> +static int mt25qu512a_post_bfpt_fixup(struct spi_nor *nor,
> +                               const struct sfdp_parameter_header
> *bfpt_header,
> +                               const struct sfdp_bfpt *bfpt)
> +{
> +       nor->flags &= ~SNOR_F_HAS_16BIT_SR;
> +       return 0;
> +}
> +
> +static struct spi_nor_fixups mt25qu512a_fixups = {
> +       .post_bfpt = mt25qu512a_post_bfpt_fixup,
> +};
> +
>   static const struct flash_info st_nor_parts[] = {
>          {
>                  .name = "m25p05-nonjedec",
> @@ -405,10 +417,10 @@ static const struct flash_info st_nor_parts[] = {
>          }, {
>                  .id = SNOR_ID(0x20, 0xbb, 0x20, 0x10, 0x44, 0x00),
>                  .name = "mt25qu512a",
> -               .size = SZ_64M,
> -               .no_sfdp_flags = SECT_4K | SPI_NOR_DUAL_READ |
> SPI_NOR_QUAD_READ,
> -               .fixup_flags = SPI_NOR_4B_OPCODES,
> +               .flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB |
> SPI_NOR_4BIT_BP |
> +                        SPI_NOR_BP3_SR_BIT6,
>                  .mfr_flags = USE_FSR,
> +               .fixups = &mt25qu512a_fixups,
>          }, {
>                  .id = SNOR_ID(0x20, 0xbb, 0x20),
>                  .name = "n25q512a",
> 
> cut


Thanks. Yes, this post  BFPT fixup resolves lock/unlock issue and
I don't see HAS_16BIT_SR flag in params.


Datasheet is public: 
https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_512_abb_0.pdf?rev=b259aadc3bea49ea8210a41c9ad58211 


>> If yes, please add some prints in sfdp.c to determine where it's set,
>> either in BFPT_DWORD15_QER_SR2_BIT1 or BFPT_DWORD15_QER_SR2_BIT1_NO_RD
>> Is the datasheet for this flash public? Would you send me a link to it
>> please?
>>
>> Cheers,
>> ta