[PATCH v2] drm: bridge: synopsys/dw-hdmi: Provide default configuration function for HDMI 2.0 PHY

From: Jose Abreu
Date: Fri Jun 23 2017 - 05:37:16 EST

Currently HDMI 2.0 PHYs do not have a default configuration function.

As *some* of the HDMI 2.0 PHYs have the same register layout as the 3D
PHYs we can provide the same default configuration function for both
and still let user overwrite this with custom configuration function
if needed.

If, for some reason, the PHY is custom or has a register different
register layout then custom configuration function *must* be provided
in order for the system to work correctly. As we prefer the pdata
provided configuration function over the internal one this change
will not make any impact in custom platforms.

This patch is based on today's drm-misc-next branch.

Signed-off-by: Jose Abreu <joabreu@xxxxxxxxxxxx>
Tested-by: Mark Yao <mark.yao@xxxxxxxxxxxxxx>
Cc: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Cc: Mark Yao <mark.yao@xxxxxxxxxxxxxx>
Cc: Carlos Palminha <palminha@xxxxxxxxxxxx>
Cc: Heiko StÃbner <heiko@xxxxxxxxx>

Changes in v2:
- Rebased and refrased commit message

Hi All,

There as been a little confusion about dw-hdmi phys so I will expand a little bit
here so that I can base my decision about this patch and why does it only works
in some platforms.

First, if you read dw-hdmi.c code, you will see that there is an identification
register for the phy type being used. Unfortunatelly, this only states the phy type
and not the phy version.

Second, we have many HDMI 2.0 phys (so, same phy type: 0xf3) but, as you may have guessed,
HW team decided to change regbank between some versions.

Third and last, each phy in a SoC has unique characteristics, so each phy (event if
they are the same version) will have different PLL configuration parameters.

Given all this I managed to conclude that Mark's phy is still an HDMI 2.0 phy but with
the same register layout as previous 3D PHY's. I found at least 2 phys with the same
register layout and only 1 phy which has a different layout, so I think majority wins
here and we should let the default configuration function for HDMI 2.0 phys be the same
one as the 3D.

Short story: There is no way to correctly identify, at runtime, the phy version being
used by the controller so we can't provide a default configuration function. We can,
however assume that most of the HDMI 2.0 phys will have the 3D layout BUT each developer
must confirm that the layout in its SoC is the expected one and if not, provide a custom
configuration function.

Best regards,
Jose Miguel Abreu

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index ead1124..10c8d8c 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2170,6 +2170,7 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
.name = "DWC HDMI 2.0 TX PHY",
.gen = 2,
.has_svsret = true,
+ .configure = hdmi_phy_configure_dwc_hdmi_3d_tx,
}, {
.name = "Vendor PHY",