Re: [PATCH v3] drm/rcar-du: dsi: Implement DSI command TX using AXI memory access
From: Tomi Valkeinen
Date: Fri Sep 11 2026 - 01:17:35 EST
Hi,
On 10/09/2026 21:19, Marek Vasut wrote:
Currently, the driver supports register access mode for DSI commandReviewed-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx>
transfer, which limits both TX and RX to only 16 Bytes long packets.
Implement support for DSI command TX using AXI memory access mode,
which extends the packet transfer length up to 128 Bytes long in LP
and 1024 Bytes long in HS. Support for DSI command RX using the AXI
access mode is not implemented due to missing test hardware.
The implementation allocates a DMAble 4k page. In case the command
transfer is longer than 16 Bytes, the payload is copied into the
page and sent out using the AXI access mode, otherwise the register
access mode is used.
Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
---
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Magnus Damm <magnus.damm@xxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Simona Vetter <simona@xxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
---
V2: - Use dma_set_mask_and_coherent() to set up global DMA mask and
drop GFP_DMA32 from dma_alloc_coherent() gfp flags.
- Fix DMA memory leak in missing fail path in rcar_mipi_dsi_probe()
and move dma_alloc_coherent() almost to the end of the probe
function, so as much as possible of the probe function is devm
managed.
- Unregister DSI host first, then free the DMA page
V3: - Limit transfer to 1024 Bytes
---
.../gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c | 50 ++++++++++++++++---
1 file changed, 42 insertions(+), 8 deletions(-)
Tomi