drivers: add mipi_dbi_rpi_pico_pio #91350
Open
+921
−0
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
github-actions
bot
added
area: Display Controller
platform: Raspberry Pi Pico
github-actions
bot
requested review from
ajf58,
danieldegrasse,
soburi,
ThreeEights and
yonsch
Maravus
force-pushed
the
add-mipi-dbi-rpi-pico-pio
branch
2 times, most recently
from
0b9adcf to
ccc4852
Compare
kartben
reviewed
Jun 24, 2025
| const char *failed_pin = NULL; | ||
| int ret = 0; | ||
|
|
||
| mipi_dbi_pio_configure(dev); |
Comment on lines
198
to
250
| switch (split_count) { | ||
| case 4: | ||
| SET_SM_PROGRAM(3, splits[0].pin_count + splits[1].pin_count + splits[2].pin_count) | ||
| case 3: | ||
| SET_SM_PROGRAM(2, splits[0].pin_count + splits[1].pin_count) | ||
| case 2: | ||
| SET_SM_PROGRAM(1, splits[0].pin_count) | ||
| case 1: | ||
| CONFIG_SM_PROGRAM(0, 0, 1, 2) | ||
| /* 0: pull ifempty block side 1 [1] */ | ||
| split->sm.program_instructions[0] = 0x99e0; | ||
| /* 1: out pins, #pins side 0 [1] */ | ||
| split->sm.program_instructions[1] = 0x7100 | split->pin_count; | ||
| default: | ||
| break; | ||
| } |
There was a problem hiding this comment.
I'm guessing the fallthrough are intentional but please mark them as such (__fallthrough;)
| .cmd_data = GPIO_DT_SPEC_INST_GET_OR(n, dc_gpios, {}), \ | ||
| .reset = GPIO_DT_SPEC_INST_GET_OR(n, reset_gpios, {}), \ | ||
| }; \ | ||
| BUILD_ASSERT(DT_INST_PROP_LEN(n, data_gpios) < MIPI_DBI_MAX_DATA_BUS_WIDTH, \ |
There was a problem hiding this comment.
Suggested change
| BUILD_ASSERT(DT_INST_PROP_LEN(n, data_gpios) < MIPI_DBI_MAX_DATA_BUS_WIDTH, \ | |
| BUILD_ASSERT(DT_INST_PROP_LEN(n, data_gpios) <= MIPI_DBI_MAX_DATA_BUS_WIDTH, \ |
Comment on lines
42
to
43
| GPIO pins used for the parallel data bus. This must have as many entries as the bus is wide | ||
| of the selected mipi-mode. |
There was a problem hiding this comment.
second sentence is very oddly worded
soburi
reviewed
Jun 27, 2025
| switch (split->sm.sm) { | ||
| case 0: | ||
| split->dma.config.dma_slot = | ||
| data->pio == pio0 ? RPI_PICO_DMA_SLOT_PIO0_TX0 : RPI_PICO_DMA_SLOT_PIO1_TX0; |
There was a problem hiding this comment.
In the case of rp2350, there are three PIOs, so please consider supporting it if possible.
pdgendt
previously requested changes
Jun 27, 2025
|
Do not use fixed commits, squash and force push. |
Maravus
force-pushed
the
add-mipi-dbi-rpi-pico-pio
branch
2 times, most recently
from
ac5eea3 to
504e3d9
Compare
|
Would be nice if this driver could be built in CI |
Maravus
force-pushed
the
add-mipi-dbi-rpi-pico-pio
branch
2 times, most recently
from
f9ab134 to
68078d0
Compare
Maravus
force-pushed
the
add-mipi-dbi-rpi-pico-pio
branch
4 times, most recently
from
35406d8 to
2622e6c
Compare
Add mipi_dbi driver for MIPI_DBI_MODE_8080_BUS_8/9/16_BIT using PIO and DMA Signed-off-by: Christoph Schnetzler <schnetzler.christoph@gmail.com>
|
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Add mipi_dbi driver for MIPI_DBI_MODE_8080_BUS_8/9/16_BIT using PIO and DMA.
The implementation allows splitting the parallel data pins. Max 4 splits are possible as there are 4 state machines per PIO instance.
In general it works quite nice.
There is a topic to discuss though, how to determine the end of a transmission. For the data bytes one has to wait for the DMAs to finish, next the FIFOs have to be empty and at the end the PIOs need to be finished before pulling cs line high. Same for the CMD byte. There only one byte is transferred and one needs to wait only for the PIOs to finish.
The wait time is dependent on the clock div, the PIO instructions and the system clock. Right now a sleep is used. But this introduces quite a delay as context switching is possible.
One could adapt the PIO instructions to also toggle the cmd line but then one would need at least 2 PIO state machines, and it would add some additional clock cycles (probably not a big issue as it is really fast anyway).
Compared to mipi_dbi_bitbang it is currently still much faster. On my 320x240 display an animation is faded in with ~12fps. With the bitbang driver it reaches only ~3fps. Tested with an rp2040 at 125MHz.