Hi Laurent, On 05-12-2016 11:32, Laurent Pinchart wrote: > Hi Jose, > > On Monday 05 Dec 2016 10:50:19 Jose Abreu wrote: >> On 02-12-2016 15:43, Laurent Pinchart wrote: >>> On Friday 02 Dec 2016 14:24:01 Russell King - ARM Linux wrote: >>>> On Fri, Dec 02, 2016 at 01:43:28AM +0200, Laurent Pinchart wrote: >>>>> From: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> >>>>> >>>>> The dw-hdmi driver declares a dev_type to distinguish platform specific >>>>> changes. Replace this with a quirk field, so that the platform can >>>>> specify the required quirks for the driver, rather than the driver >>>>> becoming conditional on multiple platforms. >>>>> >>>>> As part of this, we rename the dw-hdmi 'spare' which is defined as the >>>>> SVSRET bit in later documentation. >>>> I'd really prefer that we did not go down the broken route of adding >>>> a set of "quirk" flags - look at what a mess SDHCI has become through >>>> allowing that kind of practice. >>>> >>>> I'd much rather we find a saner structure to this - and we know that >>>> the hardware has ID registers in it which can be used (so far) to >>>> identify the buggy hardware. >>> I'd much prefer something that would allow runtime identification of the >>> device and the corresponding actions to be taken. However, the amount of >>> documentation we have on the DWC HDMI TX IP core (and the associated PHY) >>> is pretty limited, given that Synopsys doesn't make the documentation >>> available publicly. Changes made to the IP core by integrators could >>> complicate this further. I'm trying to gather as much information as >>> possible to make clean the code up, for instance by trying to identify >>> the PHYs used on the various platforms we support. Progress is slow on >>> that front, there isn't enough leaked information available online :-) I >>> haven't given up though, but I'll need more time. >>> >>> I don't like quirks much either. They are however already used today, even >>> if we trigger them through dev_type instead of quirk flags. This patch >>> came from a previous version found in a BSP that simply sprinkled several >>> if (hdmi-> dev_type == RCAR_HDMI) through the code. For instance, >>> >>> - if (hdmi->dev_type == RK3288_HDMI) >>> + if (hdmi->dev_type == RK3288_HDMI || hdmi->dev_type == RCAR_HDMI) >>> dw_hdmi_phy_enable_spare(hdmi, 1); >>> >>> which I think is worse than flags as it would quickly degenerate to >>> spaghetti code. >>> >>> For this specific case, we've managed to identify that on Renesas >>> platforms the bit set by this function is called SVSRET. Its usage isn't >>> clear yet, but I suspect it to control one of the PHY input control >>> signals, like the other bits in the same register. I'm trying to get more >>> information to clean the implementation further, hopefully with a way to >>> determine whether the signal is used based on PHY identification. >> SVSRET is a low power mode consumption and is a PHY input signal >> as you suggested. > Thank you for the confirmation. Would you happen to know what SVSRET stands > for ? Have no info about that. Sorry. > >> Most of the configurable input signals of the PHY are available by the >> controller regbank. I don't think it is possible to detect this at runtime, >> I think you have at least to hardcode which version of the PHY you are >> using. >> >> I would suggest that maybe all the PHY logic should be extracted and then >> use callbacks to glue controller and phy. Then, depending on the PHY you >> could use empty stubs if, for example, a given PHY did not support SVSRET. >> Still, I don't know if this is the best option. What I do know is that there >> are a large number of PHY's with different flavors that can use the same >> controller. The controller has different versions also, and each version can >> have quirks but I think it would be easier to manage this driver if we had a >> clear distinction between PHY and controller. > Agreed, I'd like to go in that direction. What makes it quite difficult is the > lack of documentation about the PHYs :-) I've found six different PHY types > that can be identified by the CONFIG2_ID register: > > Bits | Field | Description > ------------------------------------------------------------------------------ > 7-0 | phytype | PHY interface > | | 0x00: Legacy PHY (HDMI TX PHY) > | | 0xb2: MHL PHY + HEAC PHY > | | 0xc2: MHL PHY > | | 0xe2: HDMI 3D TX PHY + HEAC PHY > | | 0xf2: HDMI 3D TX PHY > | | 0xf3: HDMI2 TX PHY > > I'm sure there's more than that. In particular I wonder how external vendor > PHYs are identified. 0xFE. > > I'm also wondering whether there's a need to keep support for the legacy PHY > signals (ENTMDS and PDZ in the PHY_CONF0 register). As far as I understand > they're not used by the Gen2 PHYs (including the external vendor PHYs), but I > can't confirm that without more documentation (although I could test that on > the platforms I have access to). You are correct. Not available on Gen2 and on external phys. >>> This is all work in progress, and if anyone has access to any >>> documentation and can provide additional information I'll be grateful. >>> >>>>> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> >>>>> Signed-off-by: Laurent Pinchart >>>>> <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> >>>>> --- >>>>> >>>>> drivers/gpu/drm/bridge/dw-hdmi.c | 14 ++++++-------- >>>>> drivers/gpu/drm/bridge/dw-hdmi.h | 4 ++-- >>>>> drivers/gpu/drm/imx/dw_hdmi-imx.c | 3 +-- >>>>> drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 2 +- >>>>> include/drm/bridge/dw_hdmi.h | 12 +++++------- >>>>> 5 files changed, 15 insertions(+), 20 deletions(-) Best regards, Jose Miguel Abreu _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
