Hi Chris & Dmitry,
On 2022-04-09 04:07, Dmitry Torokhov wrote:
Hi Chris,
On Fri, Apr 08, 2022 at 04:28:57PM -0500, Chris Morgan wrote:
From: Chris Morgan <macromorgan@xxxxxxxxxxx>
For my Odroid Go Advance I noticed that the adc-joystick driver was
only reporting the y channel and on the x axis. After debugging, I
found that the driver was trying to read values from channels 0 and
1 even though my device is using channels 1 and 2. By changing the
code
to use the axis index instead of the scan index when unpacking the
data
from the buffer, the joystick begins working as expected.
This sounds like some sort of misconfiguration, as your change
effectively removes the ability of using just some ADC channels for
joystick functionality...
I agree, this sounds like either a case of misconfiguration, or an issue
in the ADC driver that this device is using.
The axis index corresponds to the iio channel associated with the
joystick, but NOT to the order at which data is sampled by ADC.
That's why each channel has a `scan_index` field. It sounds like in
Chris' case the channels have wrong scan indices.
I'd start by verifying that in the ADC driver that is being used.
In any case, this patch is wrong and removes functionality that existing
devices depend on.
Cheers,
Artur
Let's add Jonathan and Arthur for their take on this.
Signed-off-by: Chris Morgan <macromorgan@xxxxxxxxxxx>
---
drivers/input/joystick/adc-joystick.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/input/joystick/adc-joystick.c
b/drivers/input/joystick/adc-joystick.c
index 78ebca7d400a..fe3bbd0d4566 100644
--- a/drivers/input/joystick/adc-joystick.c
+++ b/drivers/input/joystick/adc-joystick.c
@@ -32,24 +32,23 @@ static int adc_joystick_handle(const void *data,
void *private)
{
struct adc_joystick *joy = private;
enum iio_endian endianness;
- int bytes, msb, val, idx, i;
+ int bytes, msb, val, i;
const u16 *data_u16;
bool sign;
bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
for (i = 0; i < joy->num_chans; ++i) {
- idx = joy->chans[i].channel->scan_index;
endianness = joy->chans[i].channel->scan_type.endianness;
msb = joy->chans[i].channel->scan_type.realbits - 1;
sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
switch (bytes) {
case 1:
- val = ((const u8 *)data)[idx];
+ val = ((const u8 *)data)[i];
break;
case 2:
- data_u16 = (const u16 *)data + idx;
+ data_u16 = (const u16 *)data + i;
/*
* Data is aligned to the sample size by IIO core.
--
2.25.1
Thanks.
