req.sample needs its own cacheline otherwise accessing req.msg fetches
it in again.
Put req onto stack as it doesn't need to be DMA save.
req.sample is kzalloced itself for DMA access.
req.command doesn't need own cache line because it will only be written to
memory on dma_map_single. req.scratch is unsed at all.
Note: This effect doesn't occur if the underlying SPI driver doesn't use
DMA at all.
Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
---
Anatolij,
could you please check the ads7845 parts?
Thanks!
drivers/input/touchscreen/ads7846.c | 92 ++++++++++++++++++-----------------
1 files changed, 48 insertions(+), 44 deletions(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index c24946f..6157a80 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -281,7 +281,7 @@ struct ser_req {
u8 command;
u8 ref_off;
u16 scratch;
- __be16 sample;
+ __be16 *sample;
struct spi_message msg;
struct spi_transfer xfer[6];
};
@@ -289,7 +289,7 @@ struct ser_req {
struct ads7845_ser_req {
u8 command[3];
u8 pwrdown[3];
- u8 sample[3];
+ u8 *sample;
struct spi_message msg;
struct spi_transfer xfer[2];
};
@@ -298,71 +298,73 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
{
struct spi_device *spi = to_spi_device(dev);
struct ads7846 *ts = dev_get_drvdata(dev);
- struct ser_req *req;
+ struct ser_req req;
int status;
int use_internal;
- req = kzalloc(sizeof *req, GFP_KERNEL);
- if (!req)
+ memset(&req, 0, sizeof(req));
+
+ req.sample = kzalloc(sizeof *(req.sample), GFP_KERNEL);
+ if (!req.sample)
return -ENOMEM;
- spi_message_init(&req->msg);
+ spi_message_init(&req.msg);
/* FIXME boards with ads7846 might use external vref instead ... */
use_internal = (ts->model == 7846);
/* maybe turn on internal vREF, and let it settle */
if (use_internal) {
- req->ref_on = REF_ON;
- req->xfer[0].tx_buf = &req->ref_on;
- req->xfer[0].len = 1;
- spi_message_add_tail(&req->xfer[0], &req->msg);
+ req.ref_on = REF_ON;
+ req.xfer[0].tx_buf = &req.ref_on;
+ req.xfer[0].len = 1;
+ spi_message_add_tail(&req.xfer[0], &req.msg);
- req->xfer[1].rx_buf = &req->scratch;
- req->xfer[1].len = 2;
+ req.xfer[1].rx_buf = &req.scratch;
+ req.xfer[1].len = 2;
/* for 1uF, settle for 800 usec; no cap, 100 usec. */
- req->xfer[1].delay_usecs = ts->vref_delay_usecs;
- spi_message_add_tail(&req->xfer[1], &req->msg);
+ req.xfer[1].delay_usecs = ts->vref_delay_usecs;
+ spi_message_add_tail(&req.xfer[1], &req.msg);
}
/* take sample */
- req->command = (u8) command;
- req->xfer[2].tx_buf = &req->command;
- req->xfer[2].len = 1;
- spi_message_add_tail(&req->xfer[2], &req->msg);
+ req.command = (u8) command;
+ req.xfer[2].tx_buf = &req.command;
+ req.xfer[2].len = 1;
+ spi_message_add_tail(&req.xfer[2], &req.msg);
- req->xfer[3].rx_buf = &req->sample;
- req->xfer[3].len = 2;
- spi_message_add_tail(&req->xfer[3], &req->msg);
+ req.xfer[3].rx_buf = req.sample;
+ req.xfer[3].len = 2;
+ spi_message_add_tail(&req.xfer[3], &req.msg);
/* REVISIT: take a few more samples, and compare ... */
/* converter in low power mode & enable PENIRQ */
- req->ref_off = PWRDOWN;
- req->xfer[4].tx_buf = &req->ref_off;
- req->xfer[4].len = 1;
- spi_message_add_tail(&req->xfer[4], &req->msg);
+ req.ref_off = PWRDOWN;
+ req.xfer[4].tx_buf = &req.ref_off;
+ req.xfer[4].len = 1;
+ spi_message_add_tail(&req.xfer[4], &req.msg);
- req->xfer[5].rx_buf = &req->scratch;
- req->xfer[5].len = 2;
- CS_CHANGE(req->xfer[5]);
- spi_message_add_tail(&req->xfer[5], &req->msg);
+ req.xfer[5].rx_buf = &req.scratch;
+ req.xfer[5].len = 2;
+ CS_CHANGE(req.xfer[5]);
+ spi_message_add_tail(&req.xfer[5], &req.msg);
mutex_lock(&ts->lock);
ads7846_stop(ts);
- status = spi_sync(spi, &req->msg);
+ status = spi_sync(spi, &req.msg);
ads7846_restart(ts);
mutex_unlock(&ts->lock);
if (status == 0) {
/* on-wire is a must-ignore bit, a BE12 value, then padding */
- status = be16_to_cpu(req->sample);
+ status = be16_to_cpu(*req.sample);
status = status >> 3;
status &= 0x0fff;
}
- kfree(req);
+ kfree(req.sample);
return status;
}
@@ -370,35 +372,37 @@ static int ads7845_read12_ser(struct device *dev, unsigned command)
{
struct spi_device *spi = to_spi_device(dev);
struct ads7846 *ts = dev_get_drvdata(dev);
- struct ads7845_ser_req *req;
+ struct ads7845_ser_req req;
int status;
- req = kzalloc(sizeof *req, GFP_KERNEL);
- if (!req)
+ memset(&req, 0, sizeof(req));
+
+ req.sample = kzalloc(3 * sizeof *(req.sample), GFP_KERNEL);
+ if (!req.sample)
return -ENOMEM;
- spi_message_init(&req->msg);
+ spi_message_init(&req.msg);
- req->command[0] = (u8) command;
- req->xfer[0].tx_buf = req->command;
- req->xfer[0].rx_buf = req->sample;
- req->xfer[0].len = 3;
- spi_message_add_tail(&req->xfer[0], &req->msg);
+ req.command[0] = (u8) command;
+ req.xfer[0].tx_buf = req.command;
+ req.xfer[0].rx_buf = req.sample;
+ req.xfer[0].len = 3;
+ spi_message_add_tail(&req.xfer[0], &req.msg);
mutex_lock(&ts->lock);
ads7846_stop(ts);
- status = spi_sync(spi, &req->msg);
+ status = spi_sync(spi, &req.msg);
ads7846_restart(ts);
mutex_unlock(&ts->lock);
if (status == 0) {
/* BE12 value, then padding */
- status = be16_to_cpu(*((u16 *)&req->sample[1]));
+ status = be16_to_cpu(*((u16 *)&req.sample[1]));
status = status >> 3;
status &= 0x0fff;
}
- kfree(req);
+ kfree(req.sample);
return status;
}
--
1.7.3.4
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