drm/tidss: Fix dss reset
authorTomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Thu, 9 Nov 2023 07:38:01 +0000 (09:38 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 25 Jan 2024 23:35:33 +0000 (15:35 -0800)
commit417d134e72f5fe57355a8cc2320a4d6d32da51d1
tree6dca808ad2d4256f948730054c99656bc395de4c
parent11e2dc2ff842b051bc5b6e1c80ce1980ffa09980
drm/tidss: Fix dss reset

[ Upstream commit bc288a927815efcf9d7f4a54d4d89c5df478c635 ]

The probe function calls dispc_softreset() before runtime PM is enabled
and without enabling any of the DSS clocks. This happens to work by
luck, and we need to make sure the DSS HW is active and the fclk is
enabled.

To fix the above, add a new function, dispc_init_hw(), which does:

- pm_runtime_set_active()
- clk_prepare_enable(fclk)
- dispc_softreset().

This ensures that the reset can be successfully accomplished.

Note that we use pm_runtime_set_active(), not the normal
pm_runtime_get(). The reason for this is that at this point we haven't
enabled the runtime PM yet and also we don't want the normal resume
callback to be called: the dispc resume callback does some initial HW
setup, and it expects that the HW was off (no video ports are
streaming). If the bootloader has enabled the DSS and has set up a
boot time splash-screen, the DSS would be enabled and streaming which
might lead to issues with the normal resume callback.

Fixes: c9b2d923befd ("drm/tidss: Soft Reset DISPC on startup")
Reviewed-by: Aradhya Bhatia <a-bhatia1@ti.com>
Link: https://lore.kernel.org/r/20231109-tidss-probe-v2-8-ac91b5ea35c0@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/gpu/drm/tidss/tidss_dispc.c