On 09/21/17 11:39, Jose Abreu wrote:

Hi Jernej,

On 20-09-2017 21:01, Jernej Skrabec wrote:

quoted

[added media mailing list due to CEC question]

This patch series adds a HDMI glue driver for Allwinner H3 SoC. For now, only
video and CEC functionality is supported. Audio needs more tweaks.

Series is based on the H3 DE2 patch series available on mailing list:
https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_pipermail_linux-2Darm-2Dkernel_2017-2DAugust_522697.html&d=DwIBAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=WHDsc6kcWAl4i96Vm5hJ_19IJiuxx_p_Rzo2g-uHDKw&m=coyfcQKSr2asrHcaCeWFmAP_9nkFkRK8s7Uw5bmVei4&s=JCFaMXK1MmZ3jE745_YcqZhZkaqtc6UapGfSSapcz_s&e= 
(ignore patches marked with [NOT FOR REVIEW NOW] tag)

Patch 1 adds support for polling plug detection since custom PHY used here
doesn't support HPD interrupt.

Patch 2 enables overflow workaround for v1.32a. This HDMI controller exhibits
same issues as HDMI controller used in iMX6 SoCs.

Patch 3 adds CLK_SET_RATE_PARENT to hdmi clock.

Patch 4 adds dt bindings documentation.

Patch 5 adds actual H3 HDMI glue driver.

Patch 6 and 7 add HDMI node to DT and enable it where needed.

Allwinner used DW HDMI controller in a non standard way:
- register offsets obfuscation layer, which can fortunately be turned off
- register read lock, which has to be disabled by magic number
- custom PHY, which have to be initialized before DW HDMI controller
- non standard clocks
- no HPD interrupt

Because of that, I have two questions:
- Since HPD have to be polled, is it enough just to enable poll mode? I'm
  mainly concerned about invalidating CEC address here.

You mean you get no interrupt when HPD status changes? Hans can
answer this better but then you will need to invalidate the cec
physical address yourself because right now its invalidated in
the dw-hdmi irq handler (see dw_hdmi_irq()).

That's correct. When the HPD goes low you need to call cec_notifier_phys_addr_invalidate()
to invalidate the physical address. This is not terribly time sensitive, i.e.
checking this once a second would be quick enough.

Regards,

	Hans