[U-Boot] [PATCH v3 1/9] sf: Update SST flash params

[Bin Meng]

Hi Jagan,

On Tue, Apr 21, 2015 at 8:47 PM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
> Hi Bin,
>
> On 20 April 2015 at 15:02, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Jagan,
>>
>> On Fri, Apr 17, 2015 at 4:48 PM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>> Hi Bin,
>>>
>>> On 17 April 2015 at 07:14, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>> Hi Jagan,
>>>>
>>>> On Fri, Apr 17, 2015 at 2:09 AM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>>>> Hi Bin,
>>>>>
>>>>> I think you have a different interpretation of sector size here-
>>>>>
>>>>> /* The size listed here is what works with SPINOR_OP_SE, which isn't
>>>>>  * necessarily called a "sector" by the vendor.
>>>>>  */
>>>>> Say for example SST25VF040B has 8 sectors of which each sector size is
>>>>> 64 * 1024 out of this we can use 4K sector erase or 32K sector erase or
>>>>> 64K sector erase through flags.
>>>>>
>>>>> Linux does follow the same-
>>>>>         /* SST -- large erase sizes are "overlays", "sectors" are 4K */
>>>>>         { "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8, SECT_4K |
>>>>> SST_WRITE) },
>>>>>         { "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16, SECT_4K |
>>>>> SST_WRITE) },
>>>>>         { "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32, SECT_4K |
>>>>> SST_WRITE) },
>>>>>         { "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64, SECT_4K |
>>>>> SST_WRITE) },
>>>>>
>>>>> Please check it.
>>>>
>>>>
>>>> Yes, I know this pretty well. And I want to change this behavior, as
>>>> my cover letter says.
>>>>
>>>> Currently the 'sf erase' command operates on a 64KB granularity, while
>>>> the actual erase command is 4KB granularity, which is inconsistent and
>>>> causes confusion.
>>>
>>> It never related to 'sf erase' instead based on the 'params->flags'
>>> sf_probe will decide which erase_cmd with erase_size will use.
>>
>> No, it is related. See cmd_sf.c:
>
> I'm not getting your point- how could it erase use 64K sector size
> instead of 4K.

It indeed erases 64K sector size. You need check the logic in
spi_flash_validate_params().

> Suppose the sector size is 4K
>
> flash->sector_size = 0x1000
> 1.  erase 4K  len flash (it's total erase length)
>
> # sf erase 0x0 0x1000
>
>   len_arg = simple_strtoul(arg, &ep, 16);
>  gives - 0x1000
>
>    *len becomes 0x1000
>
> 2.  erase 4K+1 len flash
>
> # sf erase 0x0 +0x1001
>
>   len_arg = simple_strtoul(arg, &ep, 16);
>  gives - 0x1001
>
>  *len becomes 0x2000
>
> All the way when it goes to sf_ops.c erase will take by means of
> erase_size which is assigned in sf_probe.c based on flags like 4K
> 32K or 64K.

Regards,
Bin