Hi Eric,
On Tue, Jun 02, 2020 at 12:31:37PM -0700, Eric Anholt wrote:
On Tue, Jun 2, 2020 at 8:02 AM Dave Stevenson dave.stevenson@raspberrypi.com wrote:
Hi Maxime and Eric
On Tue, 2 Jun 2020 at 15:12, Maxime Ripard maxime@cerno.tech wrote:
Hi Eric
On Wed, May 27, 2020 at 09:54:44AM -0700, Eric Anholt wrote:
On Wed, May 27, 2020 at 8:50 AM Maxime Ripard maxime@cerno.tech wrote:
The VIDEN bit in the pixelvalve currently being used to enable or disable the pixelvalve seems to not be enough in some situations, which whill end up with the pixelvalve stalling.
In such a case, even re-enabling VIDEN doesn't bring it back and we need to clear the FIFO. This can only be done if the pixelvalve is disabled though.
In order to overcome this, we can configure the pixelvalve during mode_set_no_fb, but only enable it in atomic_enable and flush the FIFO there, and in atomic_disable disable the pixelvalve again.
What displays has this been tested with? Getting this sequencing right is so painful, and things like DSI are tricky to get to light up.
That FIFO is between the HVS and the HDMI PVs, so this was obviously tested against that. Dave also tested the DSI output IIRC, so we should be covered here.
DSI wasn't working on the first patch set that Maxime sent - I haven't tested this one as yet but will do so. DPI was working early on to both an Adafruit 800x480 DPI panel, and via a VGA666 as VGA. HDMI is obviously working. VEC is being ignored now. The clock structure is more restricted than earlier chips, so to get the required clocks for the VEC without using fractional divides it compromises the clock that other parts of the system can run at (IIRC including the ARM). That's why the VEC has to be explicitly enabled for the firmware to enable it as the only output. It's annoying, but that's just a restriction of the chip.
I'm more concerned with "make sure we don't regress pre-pi4 with this series" than "pi4 displays all work from the beginning"
I tested the DSI today on an RPI3, and I had to fix an issue with the HVS-PV muxing, but otherwise it works with this series. Otherwise, the HDMI and TXP work on the Pi3 too, I'll give a try to the VGA adapter on it next week to test DPI too.
As a side note, my DSI display without my patches gives DSI transfer timeouts at boot, since at least (mainline) 5.4, I haven't tested further back. It just stalls the modeset for a while, but the display works fine after that.
Does that ring any bell?
Maxime