The patch titled
ads7846 conversion accuracy
has been added to the -mm tree. Its filename is
ads7846-conversion-accuracy.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: ads7846 conversion accuracy
From: David Brownell <david-b@xxxxxxxxxxx>
This improves accuracy of the touchscreen and hwmon sensor readings,
addressing an issue noted by Imre Deak: there's an extra bit written before
the sample (12 bits) gets written out.
It also catches up to various comments, and makes the /proc/interrupts
entry sensible again.
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Cc: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Dmitry Torokhov <dtor_core@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/input/touchscreen/ads7846.c | 53 +++++++++++++-------------
1 files changed, 28 insertions(+), 25 deletions(-)
diff -puN drivers/input/touchscreen/ads7846.c~ads7846-conversion-accuracy drivers/input/touchscreen/ads7846.c
--- 25/drivers/input/touchscreen/ads7846.c~ads7846-conversion-accuracy Wed May 24 13:57:44 2006
+++ 25-akpm/drivers/input/touchscreen/ads7846.c Wed May 24 13:57:44 2006
@@ -36,13 +36,10 @@
/*
- * This code has been tested on an ads7846 / N770 device.
+ * This code has been heavily tested on a Nokia 770, and lightly
+ * tested on other ads7846 devices (OSK/Mistral, Lubbock).
* Support for ads7843 and ads7845 has only been stubbed in.
*
- * Not yet done: How accurate are the temperature and voltage
- * readings? (System-specific calibration should support
- * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
- *
* IRQ handling needs a workaround because of a shortcoming in handling
* edge triggered IRQs on some platforms like the OMAP1/2. These
* platforms don't handle the ARM lazy IRQ disabling properly, thus we
@@ -248,10 +245,13 @@ static int ads7846_read12_ser(struct dev
if (req->msg.status)
status = req->msg.status;
+
+ /* on-wire is a must-ignore bit, a BE12 value, then padding */
sample = be16_to_cpu(req->sample);
- sample = sample >> 4;
- kfree(req);
+ sample = sample >> 3;
+ sample &= 0x0fff;
+ kfree(req);
return status ? status : sample;
}
@@ -336,13 +336,13 @@ static void ads7846_rx(void *ads)
u16 x, y, z1, z2;
unsigned long flags;
- /* adjust: 12 bit samples (left aligned), built from
- * two 8 bit values writen msb-first.
+ /* adjust: on-wire is a must-ignore bit, a BE12 value, then padding;
+ * built from two 8 bit values written msb-first.
*/
- x = be16_to_cpu(ts->tc.x) >> 4;
- y = be16_to_cpu(ts->tc.y) >> 4;
- z1 = be16_to_cpu(ts->tc.z1) >> 4;
- z2 = be16_to_cpu(ts->tc.z2) >> 4;
+ x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
+ y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
+ z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
+ z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;
/* range filtering */
if (x == MAX_12BIT)
@@ -420,7 +420,7 @@ static void ads7846_debounce(void *ads)
m = &ts->msg[ts->msg_idx];
t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
- val = (*(u16 *)t->rx_buf) >> 3;
+ val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
/* Repeat it, if this was the first read or the read
* wasn't consistent enough. */
@@ -469,7 +469,7 @@ static void ads7846_timer(unsigned long
spin_lock_irq(&ts->lock);
if (unlikely(ts->msg_idx && !ts->pendown)) {
- /* measurment cycle ended */
+ /* measurement cycle ended */
if (!device_suspended(&ts->spi->dev)) {
ts->irq_disabled = 0;
enable_irq(ts->spi->irq);
@@ -495,11 +495,10 @@ static irqreturn_t ads7846_irq(int irq,
spin_lock_irqsave(&ts->lock, flags);
if (likely(ts->get_pendown_state())) {
if (!ts->irq_disabled) {
- /* REVISIT irq logic for many ARM chips has cloned a
- * bug wherein disabling an irq in its handler won't
- * work;(it's disabled lazily, and too late to work.
- * until all their irq logic is fixed, we must shadow
- * that state here.
+ /* The ARM do_simple_IRQ() dispatcher doesn't act
+ * like the other dispatchers: it will report IRQs
+ * even after they've been disabled. We work around
+ * that here. (The "generic irq" framework may help...)
*/
ts->irq_disabled = 1;
disable_irq(ts->spi->irq);
@@ -609,16 +608,20 @@ static int __devinit ads7846_probe(struc
return -EINVAL;
}
+ /* REVISIT when the irq can be triggered active-low, or if for some
+ * reason the touchscreen isn't hooked up, we don't need to access
+ * the pendown state.
+ */
if (pdata->get_pendown_state == NULL) {
dev_dbg(&spi->dev, "no get_pendown_state function?\n");
return -EINVAL;
}
- /* We'd set the wordsize to 12 bits ... except that some controllers
- * will then treat the 8 bit command words as 12 bits (and drop the
- * four MSBs of the 12 bit result). Result: inputs must be shifted
- * to discard the four garbage LSBs.
+ /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
+ * that even if the hardware can do that, the SPI controller driver
+ * may not. So we stick to very-portable 8 bit words, both RX and TX.
*/
+ spi->bits_per_word = 8;
ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
input_dev = input_allocate_device();
@@ -772,7 +775,7 @@ static int __devinit ads7846_probe(struc
if (request_irq(spi->irq, ads7846_irq,
SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,
- spi->dev.bus_id, ts)) {
+ spi->dev.driver->name, ts)) {
dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
err = -EBUSY;
goto err_free_mem;
_
Patches currently in -mm which might be from david-b@xxxxxxxxxxx are
origin.patch
ads7846-conversion-accuracy.patch
revert-gregkh-usb-usb-ohci-avoids-root-hub-timer-polling.patch
rtc-framework-driver-for-ds1307-and-similar-rtc-chips.patch
random-remove-bogus-sa_sample_random-from-at91-compact-flash-driver.patch
-
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