On 01/08/2013 05:36 PM, Tomasz Figa wrote:
On Tuesday 08 of January 2013 11:12:26 Marcus Lorentzon wrote:
On 01/08/2013 09:18 AM, Laurent Pinchart wrote:
On Thursday 27 December 2012 15:43:34 Tomasz Figa wrote:
On Monday 24 of December 2012 15:12:28 Laurent Pinchart wrote:
> On Friday 21 December 2012 11:00:52 Tomasz Figa wrote:
> > On Tuesday 18 of December 2012 08:31:30 Vikas Sajjan
wrote:
> > > On 17 December 2012 20:55, Laurent Pinchart wrote:
> > > > Hi Vikas,
> > > >
> > > > Sorry for the late reply. I now have more time to
> > > > work on CDF, so
> > > > delays should be much shorter.
> > > >
> > > > On Thursday 06 December 2012 10:51:15 Vikas Sajjan
wrote:
> > > > > Hi Laurent,
> > > > >
> > > > > I was thinking of porting CDF to samsung
> > > > > EXYNOS 5250 platform,
> > > > > what I found is that, the exynos display
> > > > > controller is MIPI DSI
> > > > > based controller.
> > > > >
> > > > > But if I look at CDF patches, it has only
> > > > > support for MIPI DBI
> > > > > based Display controller.
> > > > >
> > > > > So my question is, do we have any generic
> > > > > framework for MIPI DSI
> > > > > based display controller? basically I wanted
> > > > > to know, how to go
> > > > > about porting CDF for such kind of display
> > > > > controller.
> > > >
> > > > MIPI DSI support is not available yet. The only
> > > > reason for that is
> > > > that I don't have any MIPI DSI hardware to write
> > > > and test the code
> > > > with:-)
> > > >
> > > > The common display framework should definitely
> > > > support MIPI DSI. I
> > > > think the existing MIPI DBI code could be used as
> > > > a base, so the
> > > > implementation shouldn't be too high.
> > > >
> > > > Yeah, i was also thinking in similar lines, below
> > > > is my though for
> > > > MIPI DSI support in CDF.
> > >
> > > o MIPI DSI support as part of CDF framework will
> > > expose
> > > § mipi_dsi_register_device(mpi_device) (will be
> > > called mach-xxx-dt.c
> > > file )
> > > § mipi_dsi_register_driver(mipi_driver, bus ops)
> > > (will be called
> > > from platform specific init driver call )
> > > · bus ops will be
> > > o read data
> > > o write data
> > > o write command
> > > § MIPI DSI will be registered as bus_register()
> > >
> > > When MIPI DSI probe is called, it (e.g., Exynos or
> > > OMAP MIPI DSI)
> > > will initialize the MIPI DSI HW IP.
> > >
> > > This probe will also parse the DT file for MIPI DSI
> > > based panel, add
> > > the panel device (device_add() ) to kernel and
> > > register the display
> > > entity with its control and video ops with CDF.
> > >
> > > I can give this a try.
> >
> > I am currently in progress of reworking Exynos MIPI DSIM
> > code and
> > s6e8ax0 LCD driver to use the v2 RFC of Common Display
> > Framework. I
> > have most of the work done, I have just to solve several
> > remaining
> > problems.
>
> Do you already have code that you can publish ? I'm
> particularly
> interested (and I think Tomi Valkeinen would be as well) in
> looking at
> the DSI operations you expose to DSI sinks (panels,
> transceivers, ...).
Well, I'm afraid this might be little below your expectations, but
here's an initial RFC of the part defining just the DSI bus. I
need a bit more time for patches for Exynos MIPI DSI master and
s6e8ax0 LCD.
No worries. I was particularly interested in the DSI operations you
needed to export, they seem pretty simple. Thank you for sharing the
code.
FYI,
here is STE "DSI API":
http://www.igloocommunity.org/gitweb/?p=kernel/igloo-kernel.git;a=blob;f
=include/video/mcde.h;h=499ce5cfecc9ad77593e761cdcc1624502f28432;hb=HEAD
#l361
But it is not perfect. After a couple of products we realized that most
panel drivers want an easy way to send a bunch of init commands in one
go. So I think it should be an op for sending an array of commands at
once. Something like
struct dsi_cmd {
enum mipi_pkt_type type; /* MIPI DSI, DCS, SetPacketLen, ... */
u8 cmd;
int dataLen;
u8 *data;
}
struct dsi_ops {
int dsi_write(source, int num_cmds, struct dsi_cmd *cmds);
...
}
Yes, this should be flexible enough to cover most of (or even whole) DSI
specification.
However I'm not sure whether the dsi_write name would be appropriate,
since DSI packet types include also read and special transactions. So,
according to DSI terminology, maybe dsi_transaction would be better?
I think read should still be separate. At least on my HW read and write
are quite different. But all "transactions" are very much the same in HW
setup. The ... was dsi_write etc ;) Like set_max_packet_size should
maybe be an ops. Since only the implementer of the "video source" will
know what the max read return packet size for that DSI IP is. The panels
don't know that. Maybe another ops to retrieve some info about the caps
of the video source would help that. Then a helper could call that and
then the dsi_write one.
And I think I still prefer the dsi_bus in favor of the abstract video
source. It just looks like a home made bus with bus-ops ... can't you do
something similar using the normal driver framework? enable/disable
looks like suspend/resume, register/unregister_vid_src is like
bus_(un)register_device, ... the video source anyway seems unattached
to the panel stuff with the find_video_source call.
DSI needs specific power management. It's necessary to power up the panel
first to make it wait for Tinit event and then enable DSI master to
trigger such event. Only then rest of panel initialization can be
completed.
I know, we have a very complex sequence for our HDMI encoder which uses
sort of continuous DSI cmmand mode. And power/clock on sequences are
tricky to get right in our current "CDF" API (mcde_display). But I fail
to see how the current video source API is different from just using the
bus/device APIs.
Also, as discussed in previous posts, some panels might use DSI only for
video data and another interface (I2C, SPI) for control data. In such case
it would be impossible to represent such device in a reasonable way using
current driver model.
I understand that you need to get hold of both the control and data bus
device in the driver. (Toshiba DSI-LVDS bridge is a good example and
commonly used "encoder" that can use both DSI and I2C control
interface.) But the control bus you get from device probe, and I guess
you could call bus_find_device_by_name(dsi_bus, "mydev") and return the
"datadev" which will have access to dsi bus ops just as you call
find_video_source("mysource") to access the "databus" ops directly with
a logical device (display entity).
I'm not saying I would refuse to use video sources. I just think the two
models are so similar so it would be worth exploring how a device model
style API would look like and to compare against.
/BR
/Marcus
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