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Subject[PATCH v11 03/56] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary
Date
From: Nick Dyer <nick.dyer@itdev.co.uk>

The workaround of reading all messages until an invalid is received is a
way of forcing the CHG line high, which means that when using
edge-triggered interrupts the interrupt can be acquired.

With level-triggered interrupts the workaround is unnecessary.

Also, most recent maXTouch chips have a feature called RETRIGEN which, when
enabled, reasserts the interrupt line every cycle if there are messages
waiting. This also makes the workaround unnecessary.

Note: the RETRIGEN feature is only in some firmware versions/chips, it's
not valid simply to enable the bit.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
(cherry picked from ndyer/linux/for-upstream commit 1ae4e8281e491b22442cd5acdfca1862555f8ecb)
[gdavis: Fix conflicts due to v4.6-rc7 commit eb43335c4095 ("Input:
atmel_mxt_ts - use mxt_acquire_irq in mxt_soft_reset").]
Signed-off-by: George G. Davis <george_davis@mentor.com>
[jiada: reset use_retrigen_workaround at beginning of mxt_check_retrigen()
call mxt_check_retrigen() after mxt_acquire_irq() in mxt_initialize()
replace white-spaces with tab for MXT_COMMS_RETRIGEN]
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 51 ++++++++++++++++++++++--
1 file changed, 48 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 49bdf5cf3a0d..3f1ebe14802f 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -20,6 +20,7 @@
#include <linux/i2c.h>
#include <linux/input/mt.h>
#include <linux/interrupt.h>
+#include <linux/irq.h>
#include <linux/of.h>
#include <linux/property.h>
#include <linux/slab.h>
@@ -129,6 +130,7 @@ struct t9_range {
/* MXT_SPT_COMMSCONFIG_T18 */
#define MXT_COMMS_CTRL 0
#define MXT_COMMS_CMD 1
+#define MXT_COMMS_RETRIGEN BIT(6)

/* MXT_DEBUG_DIAGNOSTIC_T37 */
#define MXT_DIAGNOSTIC_PAGEUP 0x01
@@ -308,6 +310,7 @@ struct mxt_data {
struct t7_config t7_cfg;
struct mxt_dbg dbg;
struct gpio_desc *reset_gpio;
+ bool use_retrigen_workaround;

/* Cached parameters from object table */
u16 T5_address;
@@ -318,6 +321,7 @@ struct mxt_data {
u16 T71_address;
u8 T9_reportid_min;
u8 T9_reportid_max;
+ u16 T18_address;
u8 T19_reportid;
u16 T44_address;
u8 T100_reportid_min;
@@ -1190,9 +1194,11 @@ static int mxt_acquire_irq(struct mxt_data *data)

enable_irq(data->irq);

- error = mxt_process_messages_until_invalid(data);
- if (error)
- return error;
+ if (data->use_retrigen_workaround) {
+ error = mxt_process_messages_until_invalid(data);
+ if (error)
+ return error;
+ }

return 0;
}
@@ -1282,6 +1288,33 @@ static u32 mxt_calculate_crc(u8 *base, off_t start_off, off_t end_off)
return crc;
}

+static int mxt_check_retrigen(struct mxt_data *data)
+{
+ struct i2c_client *client = data->client;
+ int error;
+ int val;
+
+ data->use_retrigen_workaround = false;
+
+ if (irq_get_trigger_type(data->irq) & IRQF_TRIGGER_LOW)
+ return 0;
+
+ if (data->T18_address) {
+ error = __mxt_read_reg(client,
+ data->T18_address + MXT_COMMS_CTRL,
+ 1, &val);
+ if (error)
+ return error;
+
+ if (val & MXT_COMMS_RETRIGEN)
+ return 0;
+ }
+
+ dev_warn(&client->dev, "Enabling RETRIGEN workaround\n");
+ data->use_retrigen_workaround = true;
+ return 0;
+}
+
static int mxt_prepare_cfg_mem(struct mxt_data *data, struct mxt_cfg *cfg)
{
struct device *dev = &data->client->dev;
@@ -1561,6 +1594,10 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)

mxt_update_crc(data, MXT_COMMAND_BACKUPNV, MXT_BACKUP_VALUE);

+ ret = mxt_check_retrigen(data);
+ if (ret)
+ goto release_mem;
+
ret = mxt_soft_reset(data);
if (ret)
goto release_mem;
@@ -1604,6 +1641,7 @@ static void mxt_free_object_table(struct mxt_data *data)
data->T71_address = 0;
data->T9_reportid_min = 0;
data->T9_reportid_max = 0;
+ data->T18_address = 0;
data->T19_reportid = 0;
data->T44_address = 0;
data->T100_reportid_min = 0;
@@ -1678,6 +1716,9 @@ static int mxt_parse_object_table(struct mxt_data *data,
object->num_report_ids - 1;
data->num_touchids = object->num_report_ids;
break;
+ case MXT_SPT_COMMSCONFIG_T18:
+ data->T18_address = object->start_address;
+ break;
case MXT_SPT_MESSAGECOUNT_T44:
data->T44_address = object->start_address;
break;
@@ -2145,6 +2186,10 @@ static int mxt_initialize(struct mxt_data *data)
if (error)
return error;

+ error = mxt_check_retrigen(data);
+ if (error)
+ return error;
+
error = mxt_sysfs_init(data);
if (error)
return error;
--
2.17.1
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