| Message ID | 20201015182710.54795-5-jacopo+renesas@jmondi.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Kieran Bingham |
| Headers | show |
| Series | media: i2c: Add support for RDACM21 camera module | expand |
Hi Jacopo, On 15/10/2020 19:27, Jacopo Mondi wrote: > 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. > > 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 89a7248f5c25..163e102199e3 100644 > --- a/drivers/media/i2c/max9286.c > +++ b/drivers/media/i2c/max9286.c > @@ -906,19 +906,29 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv) > * Probe/Remove > */ > > -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); > + Should we also clamp to min/max values at all? Probably not needed, as it's only an internal helper. > + if (chan_amplitude > 100) { > + /* It is not possible express values (100 < x < 130) */ 'possible to express' > + chan_amplitude = chan_amplitude < 130 > + ? 30 : chan_amplitude - 100; We could round < 115 to 100, and >= 115 to 130, but that's probably more effort that it's worth, so I think this is fine. I think it's really helpful to codify this parameter though: Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> > + 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 >
Hello! On 15.10.2020 21:27, Jacopo Mondi wrote: > 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. > > 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 89a7248f5c25..163e102199e3 100644 > --- a/drivers/media/i2c/max9286.c > +++ b/drivers/media/i2c/max9286.c > @@ -906,19 +906,29 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv) > * Probe/Remove > */ > > -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 express values (100 < x < 130) */ "To express", perhaps? > + 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); > } > [...] MBR, Sergei
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c index 89a7248f5c25..163e102199e3 100644 --- a/drivers/media/i2c/max9286.c +++ b/drivers/media/i2c/max9286.c @@ -906,19 +906,29 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv) * Probe/Remove */ -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 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
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. Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org> --- drivers/media/i2c/max9286.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)