Commit 5a386b1f authored by Jacopo Mondi's avatar Jacopo Mondi Committed by Mauro Carvalho Chehab
Browse files

media: i2c: max9286: Make channel amplitude programmable 



Instrument the function that configures the reverse channel with a
programmable amplitude value.

This change serves to prepare to adjust the reverse channel amplitude
depending on the remote end high-threshold configuration.

Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: default avatarKieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: default avatarJacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent 02b57eb3

drivers/media/i2c/max9286.c

+15 −6
Original line number Diff line number Diff line
@@ -336,19 +336,28 @@ static void max9286_configure_i2c(struct max9286_priv *priv, bool localack) 
	usleep_range(3000, 5000);

}



static void max9286_reverse_channel_setup(struct max9286_priv *priv)

static void max9286_reverse_channel_setup(struct max9286_priv *priv,

					  unsigned int chan_amplitude)

{

	/* Reverse channel transmission time: default to 1. */

	u8 chan_config = MAX9286_REV_TRF(1);



	/*

	 * Reverse channel setup.

	 *

	 * - Enable custom reverse channel configuration (through register 0x3f)

	 *   and set the first pulse length to 35 clock cycles.

	 * - Increase the reverse channel amplitude to 170mV to accommodate the

	 *   high threshold enabled by the serializer driver.

	 * - Adjust reverse channel amplitude: values > 130 are programmed

	 *   using the additional +100mV REV_AMP_X boost flag

	 */

	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));

	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |

		      MAX9286_REV_AMP_X);



	if (chan_amplitude > 100) {

		/* It is not possible to express values (100 < x < 130) */

		chan_amplitude = max(30U, chan_amplitude - 100);

		chan_config |= MAX9286_REV_AMP_X;

	}

	max9286_write(priv, 0x3b, chan_config | MAX9286_REV_AMP(chan_amplitude));

	usleep_range(2000, 2500);

}
@@ -957,7 +966,7 @@ static int max9286_setup(struct max9286_priv *priv) 
	 * only. This should be disabled after the mux is initialised.

	 */

	max9286_configure_i2c(priv, true);

	max9286_reverse_channel_setup(priv);

	max9286_reverse_channel_setup(priv, 170);



	/*

	 * Enable GMSL links, mask unused ones and autodetect link