drm/omapdrm: Convert to SPDX identifier

use SPDX-License-Identifier instead of a verbose license text

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210822072323.408-1-caihuoqing@baidu.com

drm: omapdrm: Replace HTTP links with HTTPS ones

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.

Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200713122859.34135-1-grandmaster@al2klimov.de

drm/omap: hdmi4_cec: Fix CEC clock handling for PM

If CONFIG_OMAP4_DSS_HDMI_CEC is enabled in .config, deeper SoC idle
states are blocked because the CEC clock gets always enabled on init.

Let's fix the issue by moving the CEC clock handling to happen later in
hdmi_cec_adap_enable() as suggested by Hans Verkuil <hverkuil@xs4all.nl>.
This way the CEC clock gets only enabled when needed. This can be tested
by doing cec-ctl --playback to enable the CEC, and doing cec-ctl --clear
to disable it.

Let's also fix the typo for "divider" in the comments while at it.

Fixes: 8d7f934df8d8 ("omapdrm: hdmi4_cec: add OMAP4 HDMI CEC support")
Suggested-by: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190326151438.32414-1-tony@atomide.com

drm: omapdrm: hdmi4: Allocate the omap_hdmi data structure dynamically

The omap_hdmi private data structure is currently stored as a global
variable. While no platform with multiple HDMI4 encoders currently
exists nor is planned, this doesn't comply with the kernel device model
and should thus be fixed.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

omapdrm/dss/hdmi4_cec: fix interrupt handling

The omap4 CEC hardware cannot tell a Nack from a Low Drive from an
Arbitration Lost error, so just report a Nack, which is almost
certainly the reason for the error anyway.

This also simplifies the implementation. The only three interrupts
that need to be enabled are:

Transmit Buffer Full/Empty Change event: triggered when the
transmit finished successfully and cleared the buffer.

Receiver FIFO Not Empty event: triggered when a message was received.

Frame Retransmit Count Exceeded event: triggered when a transmit
failed repeatedly, usually due to the message being Nacked. Other
reasons are possible (Low Drive, Arbitration Lost) but there is no
way to know. If this happens the TX buffer needs to be cleared
manually.

While testing various error conditions I noticed that the hardware
can receive messages up to 18 bytes in total, which exceeds the legal
maximum of 16. This could cause a buffer overflow, so we check for
this and constrain the size to 16 bytes.

The old incorrect interrupt handler could cause the CEC framework to
enter into a bad state because it mis-detected the "Start Bit Irregularity
event" as an ARB_LOST transmit error when it actually is a receive error
which should be ignored.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Henrik Austad <haustad@cisco.com>
Tested-by: Henrik Austad <haustad@cisco.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

omapdrm: hdmi4_cec: signedness bug in hdmi4_cec_init()

"ret" needs to be signed for the error handling to work.

Fixes: 8d7f934df8d8 ("omapdrm: hdmi4_cec: add OMAP4 HDMI CEC support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

omapdrm: hdmi4_cec: add OMAP4 HDMI CEC support

Add the source and header for the OMAP4 HDMI CEC support.

This code is not yet hooked up, that will happen in the next patch.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>