Re: [PATCH 05/14] media: sun6i-csi: Only configure the interface data width for parallel

Paul Kocialkowski
2020-10-27T09:31:36Z

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Hi,

On Mon 26 Oct 20, 17:00, Maxime Ripard wrote:
> On Fri, Oct 23, 2020 at 07:45:37PM +0200, Paul Kocialkowski wrote:
> > Bits related to the interface data width do not have any effect when
> > the CSI controller is taking input from the MIPI CSI-2 controller.
>
> I guess it would be clearer to mention that the data width is only
> applicable for parallel here.

Understood, will change the wording in the next version.

> > In prevision of adding support for this case, set these bits
> > conditionally so there is no ambiguity.
> >
> > Co-developed-by: Kévin L'hôpital <kevin.lhopital@bootlin.com>
> > Signed-off-by: Kévin L'hôpital <kevin.lhopital@bootlin.com>
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> > .../platform/sunxi/sun6i-csi/sun6i_csi.c | 42 +++++++++++--------
> > 1 file changed, 25 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 5d2389a5cd17..a876a05ea3c7 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -378,8 +378,13 @@ static void sun6i_csi_setup_bus(struct sun6i_csi_dev *sdev)
> > unsigned char bus_width;
> > u32 flags;
> > u32 cfg;
> > + bool input_parallel = false;
> > bool input_interlaced = false;
> >
> > + if (endpoint->bus_type == V4L2_MBUS_PARALLEL ||
> > + endpoint->bus_type == V4L2_MBUS_BT656)
> > + input_parallel = true;
> > +
> > if (csi->config.field == V4L2_FIELD_INTERLACED
> > || csi->config.field == V4L2_FIELD_INTERLACED_TB
> > || csi->config.field == V4L2_FIELD_INTERLACED_BT)
> > @@ -395,6 +400,26 @@ static void sun6i_csi_setup_bus(struct sun6i_csi_dev *sdev)
> > CSI_IF_CFG_HREF_POL_MASK | CSI_IF_CFG_FIELD_MASK |
> > CSI_IF_CFG_SRC_TYPE_MASK);
> >
> > + if (input_parallel) {
> > + switch (bus_width) {
> > + case 8:
> > + cfg |= CSI_IF_CFG_IF_DATA_WIDTH_8BIT;
> > + break;
> > + case 10:
> > + cfg |= CSI_IF_CFG_IF_DATA_WIDTH_10BIT;
> > + break;
> > + case 12:
> > + cfg |= CSI_IF_CFG_IF_DATA_WIDTH_12BIT;
> > + break;
> > + case 16: /* No need to configure DATA_WIDTH for 16bit */
> > + break;
> > + default:
> > + dev_warn(sdev->dev, "Unsupported bus width: %u\n",
> > + bus_width);
> > + break;
> > + }
> > + }
> > +
> > if (input_interlaced)
> > cfg |= CSI_IF_CFG_SRC_TYPE_INTERLACED;
> > else
> > @@ -440,23 +465,6 @@ static void sun6i_csi_setup_bus(struct sun6i_csi_dev *sdev)
> > break;
> > }
> >
> > - switch (bus_width) {
> > - case 8:
> > - cfg |= CSI_IF_CFG_IF_DATA_WIDTH_8BIT;
> > - break;
> > - case 10:
> > - cfg |= CSI_IF_CFG_IF_DATA_WIDTH_10BIT;
> > - break;
> > - case 12:
> > - cfg |= CSI_IF_CFG_IF_DATA_WIDTH_12BIT;
> > - break;
> > - case 16: /* No need to configure DATA_WIDTH for 16bit */
> > - break;
> > - default:
> > - dev_warn(sdev->dev, "Unsupported bus width: %u\n", bus_width);
> > - break;
> > - }
> > -
>
> Is there any reason to move it around?

The main reason is cosmetics: input_parallel is introduced to match the already
existing input_interlaced variable, so it made sense to me to have both of these
conditionals one after the other instead of spreading them randomly.

I can mention this in the commit log if you prefer.

--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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