From: Jacopo Mondi <jacopo+renesas@jmondi.org>
To: kieran.bingham+renesas@ideasonboard.com,
laurent.pinchart+renesas@ideasonboard.com,
niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org
Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>,
linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-kernel@vger.kernel.org, Hyun Kwon <hyunk@xilinx.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Subject: [PATCH v4 4/8] media: i2c: max9286: Make channel amplitude programmable
Date: Thu, 12 Nov 2020 17:27:25 +0100 [thread overview]
Message-ID: <20201112162729.101384-5-jacopo+renesas@jmondi.org> (raw)
In-Reply-To: <20201112162729.101384-1-jacopo+renesas@jmondi.org>
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: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
drivers/media/i2c/max9286.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 526b6e557dfb..31e27d0f34f1 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -336,19 +336,29 @@ 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 = chan_amplitude < 130
+ ? 30 : 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 +967,7 @@ 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
--
2.29.1
next prev parent reply other threads:[~2020-11-12 16:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 16:27 [PATCH v4 0/8] media: i2c: Add RDACM21 camera module Jacopo Mondi
2020-11-12 16:27 ` [PATCH v4 1/8] media: i2c: Add driver for " Jacopo Mondi
2020-11-12 22:31 ` Kieran Bingham
2020-11-14 14:04 ` Jacopo Mondi
2020-11-16 9:08 ` Laurent Pinchart
2020-11-16 10:03 ` Jacopo Mondi
2020-11-16 10:20 ` Kieran Bingham
2020-11-16 11:33 ` Jacopo Mondi
2020-11-12 16:27 ` [PATCH v4 2/8] dt-bindings: media: max9286: Document 'maxim,,initial-reverse-channel-mV" Jacopo Mondi
2020-11-12 22:34 ` Kieran Bingham
2020-11-12 16:27 ` [PATCH v4 3/8] media: i2c: max9286: Break-out reverse channel setup Jacopo Mondi
2020-11-12 16:27 ` Jacopo Mondi [this message]
2020-11-12 16:27 ` [PATCH v4 5/8] media: i2c: max9286: Configure reverse channel amplitude Jacopo Mondi
2020-11-12 22:38 ` Kieran Bingham
2020-11-12 16:27 ` [PATCH v4 6/8] arm64: dts: renesas: salvator-x: Add MAX9286 expansion board Jacopo Mondi
2020-11-12 16:27 ` [PATCH v4 7/8] [DNI] arm64: dts: renesas: salvator-x-max9286: Specify channel amplitude Jacopo Mondi
2020-11-12 16:27 ` [PATCH v4 8/8] [DNI] arm64: dts: renesas: eagle: " Jacopo Mondi
2020-11-12 20:52 ` Sergei Shtylyov
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