From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
niklas.soderlund+renesas@ragnatech.se, geert@linux-m68k.org,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 16/16] media: i2c: gmsl: Use 339Kbps I2C bit-rate
Date: Mon, 22 Feb 2021 04:06:48 +0200 [thread overview]
Message-ID: <YDMRuGL1HeKeYL18@pendragon.ideasonboard.com> (raw)
In-Reply-To: <aa7d8a9c-93a0-8c14-4fe4-b831e7b45d88@ideasonboard.com>
Hi Jacopo,
Thank you for the patch.
On Thu, Feb 18, 2021 at 04:07:30PM +0000, Kieran Bingham wrote:
> On 16/02/2021 17:41, Jacopo Mondi wrote:
> > With the camera modules initialization routines now running with
> > the noise immunity threshold enabled, it is possible to restore
> > the bit rate of the I2C transactions transported on the GMSL control
> > channel to 339 Kbps.
> >
> > The 339 Kbps bit rate represents the default setting for the serializer
> > and the deserializer chips, and the setup/hold time and slave timeout
> > time in use are calibrate to support that rate.
>
> s/calibrate/calibrated/
>
> Does that mean the setup/hold time and timeouts should be adjusted based
> on the i2c speed? (which we have not been doing?)
>
> With all of your other reliability improvements, does *this* change
> alone have any difference or impact on reliability?
>
> I.e. if we go slower (stay at current speed) - would we be more reliable?
>
> Is there a reliability improvement by making this speed faster?
>
> I presume we don't have a way to convey the i2c bus speed between the
> max9286 and the max9271 currently? Seems a bit like a bus parameter....
There's a max bus speed DT parameter that we can use. And I think we
should, as, in theory at least, there's no guarantee that all the
devices behind the serializer can operate at 400kbps.
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> > drivers/media/i2c/max9286.c | 2 +-
> > drivers/media/i2c/rdacm20.c | 2 +-
> > drivers/media/i2c/rdacm21.c | 2 +-
> > 3 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> > index aa01d5bb79ef..0b620f2f8c41 100644
> > --- a/drivers/media/i2c/max9286.c
> > +++ b/drivers/media/i2c/max9286.c
> > @@ -330,7 +330,7 @@ static int max9286_i2c_mux_init(struct max9286_priv *priv)
> > static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
> > {
> > u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
> > - MAX9286_I2CMSTBT_105KBPS;
> > + MAX9286_I2CMSTBT_339KBPS;
> >
> > if (localack)
> > config |= MAX9286_I2CLOCACK;
> > diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
> > index 0632ef98eea7..d45e8b0e52a0 100644
> > --- a/drivers/media/i2c/rdacm20.c
> > +++ b/drivers/media/i2c/rdacm20.c
> > @@ -450,7 +450,7 @@ static int rdacm20_init(struct v4l2_subdev *sd, unsigned int val)
> > ret = max9271_configure_i2c(&dev->serializer,
> > MAX9271_I2CSLVSH_469NS_234NS |
> > MAX9271_I2CSLVTO_1024US |
> > - MAX9271_I2CMSTBT_105KBPS);
> > + MAX9271_I2CMSTBT_339KBPS);
> > if (ret)
> > return ret;
> >
> > diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> > index 80b6f16f87a8..552985026458 100644
> > --- a/drivers/media/i2c/rdacm21.c
> > +++ b/drivers/media/i2c/rdacm21.c
> > @@ -442,7 +442,7 @@ static int rdacm21_init(struct v4l2_subdev *sd, unsigned int val)
> > ret = max9271_configure_i2c(&dev->serializer,
> > MAX9271_I2CSLVSH_469NS_234NS |
> > MAX9271_I2CSLVTO_1024US |
> > - MAX9271_I2CMSTBT_105KBPS);
> > + MAX9271_I2CMSTBT_339KBPS);
> > if (ret)
> > return ret;
> >
--
Regards,
Laurent Pinchart
prev parent reply other threads:[~2021-02-22 2:08 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-16 17:41 [PATCH 00/16] media: i2c: GMSL reliability improvements Jacopo Mondi
2021-02-16 17:41 ` [PATCH 01/16] media: i2c: rdacm20: Enable noise immunity Jacopo Mondi
2021-02-17 12:55 ` Kieran Bingham
2021-02-22 0:49 ` Laurent Pinchart
2021-02-22 14:59 ` Jacopo Mondi
2021-02-24 20:35 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 02/16] media: i2c: rdacm20: Embedded 'serializer' field Jacopo Mondi
2021-02-17 12:56 ` Kieran Bingham
2021-02-22 0:58 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 03/16] media: i2c: rdacm20: Replace goto with a loop Jacopo Mondi
2021-02-17 13:01 ` Kieran Bingham
2021-02-22 1:05 ` Laurent Pinchart
2021-02-22 15:06 ` Jacopo Mondi
2021-02-24 20:27 ` Laurent Pinchart
2021-02-25 8:56 ` Kieran Bingham
2021-02-16 17:41 ` [PATCH 04/16] media: i2c: rdacm20: Report camera module name Jacopo Mondi
2021-02-17 13:02 ` Kieran Bingham
2021-02-22 1:06 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 05/16] media: i2c: rdacm20: Check return values Jacopo Mondi
2021-02-17 13:08 ` Kieran Bingham
2021-02-22 1:09 ` Laurent Pinchart
2021-02-22 15:08 ` Jacopo Mondi
2021-02-16 17:41 ` [PATCH 06/16] media: i2c: rdacm20: Re-work ov10635 reset Jacopo Mondi
2021-02-17 13:22 ` Kieran Bingham
2021-02-22 1:15 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 07/16] media: i2c: rdacm2x: Fix wake up delay Jacopo Mondi
2021-02-17 8:02 ` Geert Uytterhoeven
2021-02-17 13:33 ` Kieran Bingham
2021-02-22 1:18 ` Laurent Pinchart
2021-02-22 15:11 ` Jacopo Mondi
2021-02-24 20:29 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 08/16] media: i2c: max9286: Adjust parameters indent Jacopo Mondi
2021-02-17 13:36 ` Kieran Bingham
2021-02-22 1:20 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 09/16] media: i2c: rdacm21: Re-work OV10640 initialization Jacopo Mondi
2021-02-17 8:06 ` Geert Uytterhoeven
2021-02-17 13:55 ` Kieran Bingham
2021-02-22 1:27 ` Laurent Pinchart
2021-02-22 15:19 ` Jacopo Mondi
2021-02-24 20:30 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 10/16] media: i2c: max9286: Rename reverse_channel_mv Jacopo Mondi
2021-02-17 8:07 ` Geert Uytterhoeven
2021-02-18 15:06 ` Kieran Bingham
2021-02-22 1:29 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 11/16] media: i2c: max9286: Cache channel amplitude Jacopo Mondi
2021-02-17 8:08 ` Geert Uytterhoeven
2021-02-18 15:39 ` Kieran Bingham
2021-02-22 1:33 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 12/16] media: i2c: max9286: Define high " Jacopo Mondi
2021-02-18 15:39 ` Kieran Bingham
2021-02-22 1:35 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 13/16] media: i2c: rdacm2x: Implement .init() subdev op Jacopo Mondi
2021-02-17 8:17 ` Geert Uytterhoeven
2021-02-18 16:13 ` Kieran Bingham
2021-02-22 1:52 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 14/16] media: i2c: max9286: Initialize remotes when bound Jacopo Mondi
2021-02-17 8:19 ` Geert Uytterhoeven
2021-02-18 16:00 ` Kieran Bingham
2021-02-22 2:03 ` Laurent Pinchart
2021-02-16 17:41 ` [PATCH 15/16] media: i2c: max9286: Rework comments in .bound() Jacopo Mondi
2021-02-18 16:03 ` Kieran Bingham
2021-02-16 17:41 ` [PATCH 16/16] media: i2c: gmsl: Use 339Kbps I2C bit-rate Jacopo Mondi
2021-02-17 8:19 ` Geert Uytterhoeven
2021-02-18 16:07 ` Kieran Bingham
2021-02-22 2:06 ` Laurent Pinchart [this message]
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