[U-Boot] [PATCH v2 16/16] sf: Add Flag status register polling support
Simon Glass
sjg at chromium.org
Mon Jun 10 22:31:08 CEST 2013
Hi Jagan,
On Mon, Jun 10, 2013 at 8:27 AM, Jagan Teki <jagannadh.teki at gmail.com>wrote:
> Hi Simon,
>
> On Sun, Jun 9, 2013 at 9:36 PM, Jagan Teki <jagannadh.teki at gmail.com>
> wrote:
> > Hi Simon,
> >
> > On Sun, Jun 9, 2013 at 7:43 PM, Simon Glass <sjg at chromium.org> wrote:
> >> Hi Jagan,
> >>
> >> On Sat, Jun 8, 2013 at 7:44 AM, Jagan Teki <jagannadh.teki at gmail.com>
> wrote:
> >>>
> >>> 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.
> >>
> >>
> >> You have changed the implementation of spi_flash_cmd_wait_ready() so
> that
> >> instead of polling for the bit within a single SPI transaction (CS
> staying
> >> asserted) you are now doing multiple transactions.
> >>
> >> The old code for spi_flash_cmd_wait_ready() ended up with an algorithm
> like
> >> this, when you look inside the nested functions:
> >>
> >> spi_claim_bus(spi);
> >> ret = spi_xfer(spi, cmd_len * 8, cmd, NULL, SPI_XFER_BEGIN);
> >> do {
> >> ret = spi_xfer(spi, 8, NULL, &status, 0);
> >> ...
> >> }
> >> spi_xfer(spi, 0, NULL, NULL, SPI_XFER_END);
> >> spi_release_bus(spi);
> >>
> >> The new code is:
> >>
> >> do {
> >> spi_claim_bus(spi);
> >> ret = spi_xfer(spi, cmd_len * 8, cmd, NULL, SPI_XFER_BEGIN);
> >> ret = spi_xfer(spi, data_len * 8, data_out, data_in,
> SPI_XFER_END);
> >> spi_release_bus(spi);
> >> ...
> >> } while (...)
> >>
> >>
> >> Can you see the difference? The bus clain and SPI_XFER_BEGIN/END is now
> >> inside the loop.
> >
> > Understand, i thought as we do _END transfer in old code as well.
> > It could be fine to go with using common function as it will do _BEGIN
> and _END.
> >
> > What could be the problem you see if we do _BEGIN and _END on loop...?
> >
> >>
> >> Is there a reason why this change is needed? Does updating the bank
> address
> >> not work with the old code?
> >
> > It doesn't effect with banking.
> >
> > Thanks,
> > Jagan.
> >
> >>
> >> It is find to move the spi_flash_cmd_poll_bit() function into
> >> spi_flash_cmd_wait_ready() - I am not worried about that. I am only
> worried
> >> about your change of algorithm as above.
> >>
> >> Regards,
> >> Simon
> >>
> >>>
> >>>
> >>> 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
> >>> >>
> >>
>
> May be I will explore much for this, update the changes later.
> and i will remains the code as before as of now.
>
Do you mean you will keep the old status-reading algorithm, or change to
your new one?
>
> Do you have any more comments on this series.
> I will going to send v3 and planning to apply.
>
I don't have any other comments.
>
> --
> Thanks,
> Jagan.
>
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