[U-Boot] [PATCH 2/2 V3] spi: exynos: Support a delay after deactivate

[Jagan Teki]

On Thu, Jun 13, 2013 at 3:36 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Jagan,
>
> On Wed, Jun 12, 2013 at 12:51 PM, Jagan Teki <jagannadh.teki at gmail.com>
> wrote:
>>
>> Hi,
>>
>>
>> On 30-05-2013 10:49, Rajeshwari Shinde wrote:
>>>
>>> For devices that need some time to react after a spi transaction
>>> finishes, add the ability to set a delay.
>>>
>>> Implement this as a delay on the first/next transaction to avoid
>>> any delay in the fairly common case where a SPI transaction is
>>> followed by other processing.
>>>
>>> Based on:
>>> "[U-Boot] [PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"
>>
>>
>> Please use the below format for referring previous commits
>> ex:
>> "<PREVIOUS_COMMIT_HEAD>"
>> (sha1: PREVIOUS_COMMIT_ID)
>>
>> in this case
>> "spi: exynos: Support SPI_PREAMBLE mode"
>> (sha1: e4eaef8910df805d511b1cb9b2caafa7d2827fdc)
>
>
> I hope you don't mind me answering part of this...
>
>>
>>
>>
>>>
>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>> Signed-off-by: Rajeshwari Shinde <rajeshwari.s at samsung.com>
>>> ---
>>> Changes in V2:
>>>         - None.
>>> Changes in V3:
>>>         - Rebased on "[PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"
>>>   drivers/spi/exynos_spi.c |   19 +++++++++++++++++++
>>>   1 files changed, 19 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c
>>> index 01378d0..03cf503 100644
>>> --- a/drivers/spi/exynos_spi.c
>>> +++ b/drivers/spi/exynos_spi.c
>>> @@ -38,6 +38,7 @@ struct spi_bus {
>>>         struct exynos_spi *regs;
>>>         int inited;             /* 1 if this bus is ready for use */
>>>         int node;
>>> +       uint deactivate_delay_us;       /* Delay to wait after deactivate
>>> */
>>>   };
>>>
>>>   /* A list of spi buses that we know about */
>>> @@ -52,6 +53,8 @@ struct exynos_spi_slave {
>>>         enum periph_id periph_id;       /* Peripheral ID for this device
>>> */
>>>         unsigned int fifo_size;
>>>         int skip_preamble;
>>> +       struct spi_bus *bus;            /* Pointer to our SPI bus info */
>>> +       ulong last_transaction_us;      /* Time of last transaction end
>>> */
>>>   };
>>>
>>>   static struct spi_bus *spi_get_bus(unsigned dev_index)
>>> @@ -97,6 +100,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum,
>>> unsigned int cs,
>>>         }
>>>
>>>         bus = &spi_bus[busnum];
>>> +       spi_slave->bus = bus;
>>>         spi_slave->regs = bus->regs;
>>>         spi_slave->mode = mode;
>>>         spi_slave->periph_id = bus->periph_id;
>>> @@ -107,6 +111,7 @@ struct spi_slave *spi_setup_slave(unsigned int
>>> busnum, unsigned int cs,
>>>                 spi_slave->fifo_size = 256;
>>>
>>>         spi_slave->skip_preamble = 0;
>>> +       spi_slave->last_transaction_us = timer_get_us();
>>>
>>>         spi_slave->freq = bus->frequency;
>>>         if (max_hz)
>>> @@ -371,9 +376,21 @@ void spi_cs_activate(struct spi_slave *slave)
>>>   {
>>>         struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
>>>
>>> +       /* If it's too soon to do another transaction, wait */
>>> +       if (spi_slave->bus->deactivate_delay_us &&
>>> +           spi_slave->last_transaction_us) {
>>> +               ulong delay_us;         /* The delay completed so far */
>>> +               delay_us = timer_get_us() -
>>> spi_slave->last_transaction_us;
>>> +               if (delay_us < spi_slave->bus->deactivate_delay_us)
>>> +                       udelay(spi_slave->bus->deactivate_delay_us -
>>> delay_us);
>>> +       }
>>
>> Add one space
>>
>>
>>>         clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
>>>         debug("Activate CS, bus %d\n", spi_slave->slave.bus);
>>>         spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
>>> +
>>> +       /* Remember time of this transaction so we can honour the bus
>>> delay */
>>> +       if (spi_slave->bus->deactivate_delay_us)
>>> +               spi_slave->last_transaction_us = timer_get_us();
>>>   }
>>>
>>>   /**
>>> @@ -423,6 +440,8 @@ static int spi_get_config(const void *blob, int node,
>>> struct spi_bus *bus)
>>>         /* Use 500KHz as a suitable default */
>>>         bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
>>>                                         500000);
>>> +       bus->deactivate_delay_us = fdtdec_get_int(blob, node,
>>> +                                       "spi-deactivate-delay", 0);
>>>
>>>         return 0;
>>>   }
>>>
>>
>> Was this tested, usually what is the max deactivate delay?
>
>
> This was tested with 50us.
>
>>
>> In this case your are passing through dts is it?
>
>
> Yes that's right.
>
> Regards,
> Simon
>
>>
>>
>> Thanks,
>> Jagan.
>>
>>
>

Can you please send the next version patches.

--
Thanks,
Jagan.