> -----Original Message----- > From: Dmitry Torokhov [mailto:dmitry.torokhov@xxxxxxxxx] > Sent: 2009年3月13日 10:34 > To: akpm@xxxxxxxxxxxxxxxxxxxx > Cc: linux-input@xxxxxxxxxxxxxxx; Eric Miao; david-b@xxxxxxxxxxx > Subject: Re: [patch 22/22] input: ads7846: introduce platform specific way > to synchronize sampling > > Hi, > > On Wed, Mar 04, 2009 at 11:59:13AM -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > From: Eric Miao <eric.miao@xxxxxxxxxxx> > > > > Noises can be introduced when LCD signals are being driven, some platforms > > provide a signal to assist the synchronization of this sampling procedure. > > > > Signed-off-by: Eric Miao <eric.miao@xxxxxxxxxxx> > > Cc: David Brownell <david-b@xxxxxxxxxxx> > > Cc: Dmitry Torokhov <dtor@xxxxxxx> > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > --- > > > > drivers/input/touchscreen/ads7846.c | 10 ++++++++++ > > include/linux/spi/ads7846.h | 2 ++ > > 2 files changed, 12 insertions(+) > > > > diff -puN drivers/input/touchscreen/ads7846.c~input-ads7846-introduce- > platform-specific-way-to-synchronize-sampling > drivers/input/touchscreen/ads7846.c > > --- a/drivers/input/touchscreen/ads7846.c~input-ads7846-introduce- > platform-specific-way-to-synchronize-sampling > > +++ a/drivers/input/touchscreen/ads7846.c > > @@ -127,6 +127,8 @@ struct ads7846 { > > void (*filter_cleanup)(void *data); > > int (*get_pendown_state)(void); > > int gpio_pendown; > > + > > + void (*wait_for_sync)(void); > > }; > > > > /* leave chip selected when we're done, for quicker re-select? */ > > @@ -511,6 +513,10 @@ static int get_pendown_state(struct ads7 > > return !gpio_get_value(ts->gpio_pendown); > > } > > > > +static void null_wait_for_sync(void) > > +{ > > +} > > + > > /* > > * PENIRQ only kicks the timer. The timer only reissues the SPI transfer, > > * to retrieve touchscreen status. > > @@ -686,6 +692,7 @@ static void ads7846_rx_val(void *ads) > > default: > > BUG(); > > } > > + ts->wait_for_sync(); > > status = spi_async(ts->spi, m); > > if (status) > > dev_err(&ts->spi->dev, "spi_async --> %d\n", > > @@ -723,6 +730,7 @@ static enum hrtimer_restart ads7846_time > > } else { > > /* pen is still down, continue with the measurement */ > > ts->msg_idx = 0; > > + ts->wait_for_sync(); > > We are in hard IRQ context here. What is the expectation of > wait_for_sync()? How long are we waiting here? > This should be a workaround for broken hardware and I don't expect this sync time on every boards. > -- > Dmitry ?韬{.n?????%??檩??w?{.n???{炳)楹哜?^n?■???h?璀?｛?夸z罐?+€?zf＂?????i?????_璁?:+v??撸?
