em28xx: Select reg wait time based on chip ID

From: Mauro Carvalho Chehab <mchehab@infradead.org>

This is more conservative than just removing the msleep() from
em28xx_write_regs_req(), since some old hardware may still need it.
So, it will remove the sleep time only for those chips where this
removal were tested.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

4 files changed, 20 insertions, 4 deletions

diff --git a/linux/drivers/media/video/em28xx/em28xx-cards.c b/linux/drivers/media/video/em28xx/em28xx-cards.c
index 3ad6cfb82..cf59a16d1 100644
--- a/linux/drivers/media/video/em28xx/em28xx-cards.c
+++ b/linux/drivers/media/video/em28xx/em28xx-cards.c
@@ -528,6 +528,20 @@ static void em28xx_set_model(struct em28xx *dev)
  */
 void em28xx_pre_card_setup(struct em28xx *dev)
 {
+	int rc;
+
+	dev->wait_after_write = 5;
+	rc = em28xx_read_reg(dev, CHIPID_REG);
+	if (rc > 0) {
+		switch (rc) {
+		case 36:
+			em28xx_info("chip ID is em2882/em2883\n");
+			dev->wait_after_write = 0;
+			break;
+		default:
+			em28xx_info("em28xx chip ID = %d\n", rc);
+		}
+	}
 	em28xx_set_model(dev);
 
 	/* request some modules */
diff --git a/linux/drivers/media/video/em28xx/em28xx-core.c b/linux/drivers/media/video/em28xx/em28xx-core.c
index baf3ad22f..ea86974e3 100644
--- a/linux/drivers/media/video/em28xx/em28xx-core.c
+++ b/linux/drivers/media/video/em28xx/em28xx-core.c
@@ -153,6 +153,9 @@ int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
 	ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), req,
 			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
 			      0x0000, reg, bufs, len, HZ);
+	if (dev->wait_after_write)
+		msleep(dev->wait_after_write);
+
 	kfree(bufs);
 	return ret;
 }
diff --git a/linux/drivers/media/video/em28xx/em28xx-video.c b/linux/drivers/media/video/em28xx/em28xx-video.c
index 1c0449b65..648aefc63 100644
--- a/linux/drivers/media/video/em28xx/em28xx-video.c
+++ b/linux/drivers/media/video/em28xx/em28xx-video.c
@@ -2008,10 +2008,6 @@ static int em28xx_init_dev(struct em28xx **devhandle, struct usb_device *udev,
 	dev->em28xx_read_reg_req = em28xx_read_reg_req;
 	dev->is_em2800 = em28xx_boards[dev->model].is_em2800;
 
-	errCode = em28xx_read_reg(dev, CHIPID_REG);
-	if (errCode >= 0)
-		em28xx_info("em28xx chip ID = %d\n", errCode);
-
 	em28xx_pre_card_setup(dev);
 
 	errCode = em28xx_config(dev);
diff --git a/linux/drivers/media/video/em28xx/em28xx.h b/linux/drivers/media/video/em28xx/em28xx.h
index da90cd36f..ac3e7a44b 100644
--- a/linux/drivers/media/video/em28xx/em28xx.h
+++ b/linux/drivers/media/video/em28xx/em28xx.h
@@ -342,6 +342,9 @@ struct em28xx {
 	unsigned int max_range_640_480:1;
 	unsigned int has_dvb:1;
 
+	/* Some older em28xx chips needs a waiting time after writing */
+	unsigned int wait_after_write;
+
 	/* GPIO sequences for tuner callback */
 	struct em28xx_reg_seq *analog_gpio, *digital_gpio;