Re: [PATCH v4 4/4] i2c: stm32f4: Fix stmpe811 get xyz data timeout issue

[dillon min <dillon.minfei@gmail.com>]

Hi Pierre-Yves, Alain

Could you help to take a look?
i really appreciate it.

Thanks,

Best Regards
Dillon

On Mon, Mar 15, 2021 at 9:00 PM Wolfram Sang <wsa@kernel.org> wrote:
>
> On Mon, Mar 15, 2021 at 08:43:54PM +0800, dillon min wrote:
> > Hi All,
> >
> > Just a gentle ping.
>
> Pierre-Yves?
>
> >
> > Regards.
> >
> > On Tue, Jun 9, 2020 at 9:27 PM <dillon.minfei@gmail.com> wrote:
> > >
> > > From: dillon min <dillon.minfei@gmail.com>
> > >
> > > as stm32f429's internal flash is 2Mbytes and compiled kernel
> > > image bigger than 2Mbytes, so we have to load kernel image
> > > to sdram on stm32f429-disco board which has 8Mbytes sdram space.
> > >
> > > based on above context, as you knows kernel running on external
> > > sdram is more slower than internal flash. besides, we need read 4
> > > bytes to get touch screen xyz(x, y, pressure) coordinate data in
> > > stmpe811 interrupt.
> > >
> > > so, in stm32f4_i2c_handle_rx_done, as i2c read slower than running
> > > in xip mode, have to adjust 'STOP/START bit set position' from last
> > > two bytes to last one bytes. else, will get i2c timeout in reading
> > > touch screen coordinate.
> > >
> > > to not take side effect, introduce IIC_LAST_BYTE_POS to support xip
> > > kernel or has mmu platform.
> > >
> > > Signed-off-by: dillon min <dillon.minfei@gmail.com>
> > > ---
> > >
> > > V4: indroduce 'IIC_LAST_BYTE_POS' to compatible with xipkernel boot
> > >
> > >  drivers/i2c/busses/i2c-stm32f4.c | 12 +++++++++---
> > >  1 file changed, 9 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-stm32f4.c b/drivers/i2c/busses/i2c-stm32f4.c
> > > index d6a69dfcac3f..97cf42ae7fa0 100644
> > > --- a/drivers/i2c/busses/i2c-stm32f4.c
> > > +++ b/drivers/i2c/busses/i2c-stm32f4.c
> > > @@ -93,6 +93,12 @@
> > >  #define STM32F4_I2C_MAX_FREQ           46U
> > >  #define HZ_TO_MHZ                      1000000
> > >
> > > +#if !defined(CONFIG_MMU) && !defined(CONFIG_XIP_KERNEL)
> > > +#define IIC_LAST_BYTE_POS 1
> > > +#else
> > > +#define IIC_LAST_BYTE_POS 2
> > > +#endif
> > > +
> > >  /**
> > >   * struct stm32f4_i2c_msg - client specific data
> > >   * @addr: 8-bit slave addr, including r/w bit
> > > @@ -439,7 +445,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> > >         int i;
> > >
> > >         switch (msg->count) {
> > > -       case 2:
> > > +       case IIC_LAST_BYTE_POS:
> > >                 /*
> > >                  * In order to correctly send the Stop or Repeated Start
> > >                  * condition on the I2C bus, the STOP/START bit has to be set
> > > @@ -454,7 +460,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> > >                 else
> > >                         stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START);
> > >
> > > -               for (i = 2; i > 0; i--)
> > > +               for (i = IIC_LAST_BYTE_POS; i > 0; i--)
> > >                         stm32f4_i2c_read_msg(i2c_dev);
> > >
> > >                 reg = i2c_dev->base + STM32F4_I2C_CR2;
> > > @@ -463,7 +469,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> > >
> > >                 complete(&i2c_dev->complete);
> > >                 break;
> > > -       case 3:
> > > +       case (IIC_LAST_BYTE_POS+1):
> > >                 /*
> > >                  * In order to correctly generate the NACK pulse after the last
> > >                  * received data byte, we have to enable NACK before reading N-2
> > > --
> > > 2.7.4
> > >

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