[U-Boot] [PATCH v3 17/17] sf: Add Flag status register polling support

[Jagan Teki]

Hi Simon,

On Thu, Jun 13, 2013 at 4:12 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Jagan,
>
> On Tue, Jun 11, 2013 at 12:23 PM, Jagannadha Sutradharudu Teki
> <jagannadha.sutradharudu-teki at xilinx.com> wrote:
>>
>> Flag status register polling is required for micron 512Mb flash
>> devices onwards, for performing erase/program operations.
>>
>> Like polling for WIP(Write-In-Progress) bit in read status register,
>> spi_flash_cmd_wait_ready will poll for PEC(Program-Erase-Control)
>> bit in flag status register.
>>
>> Signed-off-by: Jagannadha Sutradharudu Teki <jaganna at xilinx.com>
>>
>> ---
>> Changes for v3:
>>         - define the flag status code on CONFIG_SPI_FLASH_STMICRO
>> Changes for v2:
>>         - none
>>
>>  drivers/mtd/spi/spi_flash.c          | 16 +++++++++++++---
>>  drivers/mtd/spi/spi_flash_internal.h |  2 ++
>>  2 files changed, 15 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
>> index bb37f54..4f97fab0 100644
>> --- a/drivers/mtd/spi/spi_flash.c
>> +++ b/drivers/mtd/spi/spi_flash.c
>> @@ -200,12 +200,22 @@ int spi_flash_cmd_wait_ready(struct spi_flash
>> *flash, unsigned long timeout)
>>         unsigned long timebase;
>>         int ret;
>>         u8 status;
>> +       u8 check_status = 0x0;
>>         u8 poll_bit = STATUS_WIP;
>>         u8 cmd = CMD_READ_STATUS;
>>
>> +#ifdef CONFIG_SPI_FLASH_STMICRO
>> +       if (flash->size >= 0x4000000) {
>> +               poll_bit = STATUS_PEC;
>> +               check_status = poll_bit;
>> +               cmd = CMD_FLAG_STATUS;
>> +       }
>> +#endif
>> +
>
>
> Similarly to the bank addressing I think this might be better done as a
> 'poll method' rather than a hack for a particular flash type.
>

You mean to say read_status cmd and flag_status cmd need to find it on
probe it self.?
Can you please explain "better done as a 'poll method' '

> Also I worry that in a system with more than one type of flash, this code
> will fire for all flash types.

Even if the system has multiple flashes of different size, we can
probe once at a time, right?

--
Thanks,
Jagan.