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SubjectRe: [PATCH v5 1/3] mtd: spi-nor: add support for is25wp256
From
Date
Hi,

On 17/06/19 8:48 PM, Sagar Kadam wrote:
> Hello Vignesh,
>
> Thanks for your review comments.
>
> On Sun, Jun 16, 2019 at 6:14 PM Vignesh Raghavendra <vigneshr@ti.com> wrote:
>>
>> Hi,
>>
>> On 12-Jun-19 4:17 PM, Sagar Shrikant Kadam wrote:
>> [...]
>>
>>> @@ -4129,7 +4137,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>>> if (ret)
>>> return ret;
>>>
>>> - if (nor->addr_width) {
>>> + if (nor->addr_width && JEDEC_MFR(info) != SNOR_MFR_ISSI) {
>>> /* already configured from SFDP */
>>
>> Hmm, why would you want to ignore addr_width that's read from SFDP table?
>
> The SFDP table for ISSI device considered here, has addr_width set to
> 3 byte, and the flash considered
> here is 32MB. With 3 byte address width we won't be able to access
> flash memories higher address range.

Is it specific to a particular ISSI part as indicated here[1]? If so,
please submit solution agreed there i.e. use spi_nor_fixups callback

[1]https://patchwork.ozlabs.org/patch/1056049/

> Hence I have ignored the addr width from SFDP. I have verified that
> with 3 byte address width, the
> flascp util fails while verifying the written data. Please let me
> know your views on this?
>
If this affects multiple ISSI parts then:
Instead of checking for mfr code, look for SNOR_F_4B_OPCODES flag in
flash_info struct of the device and let it take precedence over SFDP in
case size is over 16MB

Regards
Vignesh

> BR,
> Sagar Kadam
>
>> Regards
>> Vignesh
>>
>>
>>> } else if (info->addr_width) {
>>> nor->addr_width = info->addr_width;
>>> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
>>> index b3d360b..ff13297 100644
>>> --- a/include/linux/mtd/spi-nor.h
>>> +++ b/include/linux/mtd/spi-nor.h
>>> @@ -19,6 +19,7 @@
>>> #define SNOR_MFR_ATMEL CFI_MFR_ATMEL
>>> #define SNOR_MFR_GIGADEVICE 0xc8
>>> #define SNOR_MFR_INTEL CFI_MFR_INTEL
>>> +#define SNOR_MFR_ISSI 0x9d /* ISSI */
>>> #define SNOR_MFR_ST CFI_MFR_ST /* ST Micro */
>>> #define SNOR_MFR_MICRON CFI_MFR_MICRON /* Micron */
>>> #define SNOR_MFR_MACRONIX CFI_MFR_MACRONIX
>>>

--
Regards
Vignesh

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