On 5/24/23 08:49, Alexander Stein wrote:
Hi Marek,
Hi,
Am Dienstag, 23. Mai 2023, 15:10:05 CEST schrieb Marek Vasut:
On 5/23/23 13:17, Alexander Stein wrote:
Hello Marek,
Hi,
Am Montag, 15. Mai 2023, 18:24:24 CEST schrieb Marek Vasut:
Add TC9595 DSI-to-DPI and DSI-to-(e)DP bridge to
DH electronics i.MX8M Plus DHCOM SoM . The bridge
is populated on the SoM, but disabled by default
unless used for display output.
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Were you actually able to access the display? E.g. reading DPCD via AUX
channel?
I only tried the full display port (the one with large plug) on the TC
evaluation kit, there I could use the aux channel. Are you testing this
bridge and running into issues ? Details please ?
Which SoC is this evaluation kit based on?
There is no SoC attached to it, it's just a breakout board for the
bridge chip. You can attach it via DSI to whichever SoC you want. So far
I tried STM32MP15xx and i.MX8MP.
Yes, I'm trying to test this bridge on imx8mp based board.
AFAICS I run into a timeout during drm connector .get_modes call, see kernel
log below.
samsung-dsim 32e60000.dsi: [drm:samsung_dsim_host_attach [samsung_dsim]]
Attached tc358767 device
tc358767 1-000f: failed to read DPCD: -110
tc358767 1-000f: failed to read display props: -110
How are you supplying clock to the TC358767 (or newer) ?
Do you supply clock from DSI or from Xtal ?
If DSI and if possible, switch to Xtal and see whether that helps.
Also check the Xtal frequency and make sure you define that correctly in DT.
Looking at the AUX_CH+/- signals, I can see the native aux request and the
(presumable) correct answer (DP_DPCD_REV register) from the display. But for
some reason the bridge runs into a aux timeout.
I can see in the DP0_AUXSTATUS register the bus gets busy (0x1) after starting
transfer. But after the tc_aux_wait_busy() call DP0_AUXSTATUS his indicating a
timeout and sync error (0x310002).
When changing the "Aux Bit Period Calculator Threshold" to 5 (register
AUXCFG1), the sync error is gone, but the timeout still happens.
The frequency used from the display is ~1MHz, which should be okay. So on the
electrical side all seems okay, but the native aux transfer don't work.
I recall DPCD read timeouts, but those were usually triggered by either
bad clock or wiring problems (the devkit wiring I used was horrible at
the beginning) from what I can recall.
