On 02/09/15 15:04, Ondrej Zary wrote:

On Wednesday 02 September 2015, Tomi Valkeinen wrote:

quoted

On 24/08/15 22:37, Ondrej Zary wrote:

quoted

i2c-algo-bit allows I2C adapters without SCL read capability to work but
fb_ddc_read fails to work on them.

Fix fb_ddc_read to work with I2C adapters not capable of reading SCL.

Signed-off-by: Ondrej Zary <redacted>
Acked-by: Krzysztof Helt <redacted>
---
 drivers/video/fbdev/core/fb_ddc.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/core/fb_ddc.c

b/drivers/video/fbdev/core/fb_ddc.c index 94322cc..22c694a 100644

--- a/drivers/video/fbdev/core/fb_ddc.c
+++ b/drivers/video/fbdev/core/fb_ddc.c

@@ -69,10 +69,11 @@ unsigned char *fb_ddc_read(struct i2c_adapter

*adapter) algo_data->setscl(algo_data->data, 1);
 		for (j = 0; j < 5; j++) {
 			msleep(10);
-			if (algo_data->getscl(algo_data->data))
+			if (algo_data->getscl &&
+			    algo_data->getscl(algo_data->data))
 				break;
 		}
-		if (j == 5)
+		if (algo_data->getscl && j == 5)
 			continue;

 		algo_data->setsda(algo_data->data, 0);

@@ -91,7 +92,8 @@ unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
 		algo_data->setscl(algo_data->data, 1);
 		for (j = 0; j < 10; j++) {
 			msleep(10);
-			if (algo_data->getscl(algo_data->data))
+			if (algo_data->getscl &&
+			    algo_data->getscl(algo_data->data))
 				break;
 		}

Aren't both of those loops pointless if there's no getscl?

They're reduced to delays - don't know how much critical they are.

I think the code gets somewhat confusing the way you did it.

Maybe instead something like:

if (algo_data->getscl) {
	the current loop & delays here;
} else {
	msleep(25); // 25 was just a guess...
}

 Tomi