Re: [PATCH v4 6/6] mtd: spi-nor: spansion: Add s25hl-t/s25hs-t IDs and fixups

[Takahiro Kuwano <tkuw584924@gmail.com>]

Hi Tudor,

On 4/9/2021 11:37 AM, Tudor.Ambarus@microchip.com wrote:
> Hi,
> 
> On 4/9/21 5:05 AM, Takahiro Kuwano wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> On 4/8/2021 7:03 PM, Tudor.Ambarus@microchip.com wrote:
>>> On 4/8/21 11:21 AM, Takahiro Kuwano wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>
>>>> Hi Tudor,
>>>>
>>>> On 4/8/2021 2:06 PM, Tudor.Ambarus@microchip.com wrote:
>>>>> Hi,
>>>>>
>>>>> On 3/19/21 8:58 AM, tkuw584924@gmail.com wrote:
>>>>>> +static int
>>>>>> +s25hx_t_post_bfpt_fixups(struct spi_nor *nor,
>>>>>> +                        const struct sfdp_parameter_header *bfpt_header,
>>>>>> +                        const struct sfdp_bfpt *bfpt,
>>>>>> +                        struct spi_nor_flash_parameter *params)
>>>>>> +{
>>>>>> +       int ret;
>>>>>> +       u32 addr;
>>>>>> +       u8 cfr3v;
>>>>>> +
>>>>>> +       ret = spi_nor_set_4byte_addr_mode(nor, true);
>>>>>> +       if (ret)
>>>>>> +               return ret;
>>>>>> +       nor->addr_width = 4;
>>>>>
>>>>> Takahiro, you are bypassing the core functions. spansion_set_4byte_addr_mode()
>>>>> will be called at set_4byte_addr_mode() time, resulting in an illegal op?
>>>>>
>>>> Since the spansion_post_sfdp_fixups() adds the SNOR_F_4B_OPCODES flag,
>>>> spansion_set_4byte_addr_mode() is not called actually.
>>>
>>> right. Do we have to undo this somewhere, i.e, call
>>> spi_nor_set_4byte_addr_mode(nor, false); ?
>>>
>> No. The Read/Write Any Register commands take 3 or 4 byte address depending
>> on the Flash's current addr mode. Since the spansion_read/write_any_reg()
>> use nor->addr_width which is always 4, the Flash's addr mode must always be
>> in 4 byte mode.
> 
> If you reboot your board via cmdline, and the flash doesn't have a reset opcode,
> the flash will remain in 4 byte mode when the driver loads again. Wouldn't that
> affect the read sfdp command, since it is sent in 3 byte mode? Can you try a
> "reboot" cmd and check what happens?
> 
The Flash always takes 3 byte address in Read SFDP command regardless of
address mode. I tried reboot and confirmed it's working correctly.

Best Regards,
Takahiro


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