[U-Boot] [PATCH v2 16/16] sf: Add Flag status register polling support

[Jagan Teki]

Hi Simon,

On Sat, Jun 8, 2013 at 8:02 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Jagan,
>
> On Sat, Jun 8, 2013 at 1:32 AM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>
>> Hi Simon,
>>
>> Please let know your comments.
>>
>> I have changed the logic, but removed spi_flash_cmd_poll_bit() use
>> poll code on spi_flash_cmd_wait_ready()
>> as no other call for spi_flash_cmd_poll_bit() this.
>>
>> And also for read_status the check_status i assigned as 0,earlier it
>> has direct 0 (w/o check_status variable).
>>
>> To add the support for flag status on the same code, i define this
>> check_status.
>> I don't see any coding functionality change for now, compared to before.
>
>
> This is not the right patch, but in one of them you remove
> spi_flash_cmd_poll_bit(), so that it no longer works the same way. You will
> get lots of individual SPI transactions on the bus instead of a single one
> that reads the status byte continuously.

I couldn't understand you clearly.

Earlier all erase/write they were calling spi_flash_cmd_wait_ready
with flash, timeout values.
spi_flash_cmd_wait_ready() is intern call to spi_flash_cmd_poll_bit()
with CMD_READ_STATUS and STATUS_WIP.

In my changes I have removed spi_flash_cmd_poll_bit() as there is no
other caller except spi_flash_cmd_wait_ready()
so all polling stuff on spi_flash_cmd_wait_ready() means, still
erase/program can call spi_flash_cmd_wait_ready() with
flash, timeout and CMD_READ_STATUS and STAUS_WIP were use directly
used on spi_flash_cmd_wait_ready() instead
of passing through spi_flash_cmd_poll_bit().

Any wrong here, please comment.

Thanks,
Jagan.

>
> Do we need to change this?
>
>
>>
>>
>> --
>> Thanks,
>> Jagan.
>>
>> On Fri, May 31, 2013 at 6:22 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 v2:
>> >         - none
>> >
>> >  drivers/mtd/spi/spi_flash.c          | 15 ++++++++++++---
>> >  drivers/mtd/spi/spi_flash_internal.h |  3 +++
>> >  2 files changed, 15 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
>> > index 527423d..8cd2988 100644
>> > --- a/drivers/mtd/spi/spi_flash.c
>> > +++ b/drivers/mtd/spi/spi_flash.c
>> > @@ -195,25 +195,34 @@ 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;
>> >
>> > +       if ((flash->idcode0 == 0x20) &&
>> > +                       (flash->size >= SPI_FLASH_512MB_STMIC)) {
>> > +               poll_bit = STATUS_PEC;
>> > +               check_status = poll_bit;
>> > +               cmd = CMD_FLAG_STATUS;
>> > +       }
>> > +
>> >         timebase = get_timer(0);
>> >         do {
>> >                 WATCHDOG_RESET();
>> >
>> >                 ret = spi_flash_read_common(flash, &cmd, 1, &status, 1);
>> >                 if (ret < 0) {
>> > -                       debug("SF: fail to read read status
>> > register\n");
>> > +                       debug("SF: fail to read %s status register\n",
>> > +                               cmd == CMD_READ_STATUS ? "read" :
>> > "flag");
>> >                         return ret;
>> >                 }
>> >
>> > -               if ((status & poll_bit) == 0)
>> > +               if ((status & poll_bit) == check_status)
>> >                         break;
>> >
>> >         } while (get_timer(timebase) < timeout);
>> >
>> > -       if ((status & poll_bit) == 0)
>> > +       if ((status & poll_bit) == check_status)
>> >                 return 0;
>> >
>> >         /* Timed out */
>> > diff --git a/drivers/mtd/spi/spi_flash_internal.h
>> > b/drivers/mtd/spi/spi_flash_internal.h
>> > index ac4530f..cb7a505 100644
>> > --- a/drivers/mtd/spi/spi_flash_internal.h
>> > +++ b/drivers/mtd/spi/spi_flash_internal.h
>> > @@ -13,6 +13,7 @@
>> >  #define SPI_FLASH_SECTOR_ERASE_TIMEOUT (10 * CONFIG_SYS_HZ)
>> >
>> >  #define SPI_FLASH_16MB_BOUN            0x1000000
>> > +#define SPI_FLASH_512MB_STMIC          0x4000000
>> >
>> >  /* Common commands */
>> >  #define CMD_READ_ID                    0x9f
>> > @@ -24,6 +25,7 @@
>> >  #define CMD_PAGE_PROGRAM               0x02
>> >  #define CMD_WRITE_DISABLE              0x04
>> >  #define CMD_READ_STATUS                        0x05
>> > +#define CMD_FLAG_STATUS                        0x70
>> >  #define CMD_WRITE_ENABLE               0x06
>> >  #define CMD_ERASE_4K                   0x20
>> >  #define CMD_ERASE_32K                  0x52
>> > @@ -38,6 +40,7 @@
>> >
>> >  /* Common status */
>> >  #define STATUS_WIP                     0x01
>> > +#define STATUS_PEC                     0x80
>> >
>> >  /* Send a single-byte command to the device and read the response */
>> >  int spi_flash_cmd(struct spi_slave *spi, u8 cmd, void *response, size_t
>> > len);
>> > --
>> > 1.8.3
>>