[PATCH V8 0/7] drm: bridge: samsung-dsim: Support variable clocking

From: Adam Ford
Date: Thu May 25 2023 - 23:06:19 EST


This series fixes the blanking pack size and the PMS calculation. It then
adds support to allows the DSIM to dynamically DPHY clocks, and support
non-burst mode while allowing the removal of the hard-coded clock values
for the PLL for imx8m mini/nano/plus, and it allows the removal of the
burst-clock device tree entry when burst-mode isn't supported by connected
devices like an HDMI brige. In that event, the HS clock is set to the
value requested by the bridge chip.

This has been tested on both an i.MX8M Nano and i.MX8M Plus, and should
work on i.MX8M Mini as well. Marek Szyprowski has tested it on various
Exynos boards.

Adam Ford (6):
drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]
drm: bridge: samsung-dsim: Fetch pll-clock-frequency automatically
drm: bridge: samsung-dsim: Select GENERIC_PHY_MIPI_DPHY
drm: bridge: samsung-dsim: Dynamically configure DPHY timing
drm: bridge: samsung-dsim: Support non-burst mode
dt-bindings: bridge: samsung-dsim: Make some flags optional

Lucas Stach (1):
drm: bridge: samsung-dsim: fix blanking packet size calculation

V8: Rebase. Add dt-bindings to series as Patch 7/7

V7: Move messages indicating the optional device tree items are going
to be automatically read elsewhere was move to dev_dbg instead of
dev_info. Cleaned up some of the comments to be a bit more clear.
Eliminated a double variable assignement accidentally introduced
in V6 when some of the items were moved from patch 6 to patch 5.

V6: Squash-in an additional error fix from Lucas Stach regarding the
DPHY calcuations. Remove the dynamic_dphy variable and let
everyone use the new calculations. Move the hs_clock caching
from patch 6 to patch 5 to go along with the DPHY calcuations
since they are now based on the recorded hs_clock rate.

V5: Update error message to dev_info and change them to indicate
what is happening without sounding like an error when optional
device tree entries are missing.

V4: Undo some accidental whitespace changes, rename PS_TO_CYCLE
variables to ps and hz from PS and MHz. Remove if check
before the samsung_dsim_set_phy_ctrl call since it's
unnecessary.
Added additional tested-by and reviewed-by comments.
Squash patches 6 and 7 together since the supporting
non-burst (patch 6) mode doesn't really work until
patch 7 was applied.

V3: When checking if the bust-clock is present, only check for it
in the device tree, and don't check the presence of the
MIPI_DSI_MODE_VIDEO_BURST flag as it breaks an existing Exynos
board.

Add a new patch to the series to select GENERIC_PHY_MIPI_DPHY in
Kconfig otherwise the build breaks on the 32-bit Exynos.

Change vco_min variable name to min_freq

Added tested-by from Chen-Yu Tsai

V2: Instead of using my packet blanking calculation, this integrates
on from Lucas Stach which gets modified later in the series to
cache the value of the HS-clock instead of having to do the
calucations again.

Instead of completely eliminating the PLL clock frequency from
the device tree, this makes it optional to avoid breaking some
Samsung devices. When the samsung,pll-clock-frequency is not
found, it reads the value of the clock named "sclk_mipi"
This also maintains backwards compatibility with older device
trees.

This also changes the DPHY calcuation from a Look-up table,
a reverse engineered algorithm which uses
phy_mipi_dphy_get_default_config to determine the standard
nominal values and calculates the cycles necessary to update
the DPHY timings accordingly.pu/drm/bridge/Kconfig | 1 +
drivers/gpu/drm/bridge/samsung-dsim.c | 141 +++++++++++++++---
include/drm/bridge/samsung-dsim.h | 4 +
4 files changed, 128 insertions(+), 27 deletions(-)

V8: Rebase onto the current master branch. Add dt-bindings to series.

V7: Move messages indicating the optional device tree items are going
to be automatically read elsewhere was move to dev_dbg instead of
dev_info. Cleaned up some of the comments to be a bit more clear.
Eliminated a double variable assignement accidentally introduced
in V6 when some of the items were moved from patch 6 to patch 5.

V6: Squash-in an additional error fix from Lucas Stach regarding the
DPHY calcuations. Remove the dynamic_dphy variable and let
everyone use the new calculations. Move the hs_clock caching
from patch 6 to patch 5 to go along with the DPHY calcuations
since they are now based on the recorded hs_clock rate.

V5: Update error message to dev_info and change them to indicate
what is happening without sounding like an error when optional
device tree entries are missing.

V4: Undo some accidental whitespace changes, rename PS_TO_CYCLE
variables to ps and hz from PS and MHz. Remove if check
before the samsung_dsim_set_phy_ctrl call since it's
unnecessary.
Added additional tested-by and reviewed-by comments.
Squash patches 6 and 7 together since the supporting
non-burst (patch 6) mode doesn't really work until
patch 7 was applied.

V3: When checking if the bust-clock is present, only check for it
in the device tree, and don't check the presence of the
MIPI_DSI_MODE_VIDEO_BURST flag as it breaks an existing Exynos
board.

Add a new patch to the series to select GENERIC_PHY_MIPI_DPHY in
Kconfig otherwise the build breaks on the 32-bit Exynos.

Change vco_min variable name to min_freq

Added tested-by from Chen-Yu Tsai

V2: Instead of using my packet blanking calculation, this integrates
on from Lucas Stach which gets modified later in the series to
cache the value of the HS-clock instead of having to do the
calucations again.

Instead of completely eliminating the PLL clock frequency from
the device tree, this makes it optional to avoid breaking some
Samsung devices. When the samsung,pll-clock-frequency is not
found, it reads the value of the clock named "sclk_mipi"
This also maintains backwards compatibility with older device
trees.

This also changes the DPHY calcuation from a Look-up table,
a reverse engineered algorithm which uses
phy_mipi_dphy_get_default_config to determine the standard
nominal values and calculates the cycles necessary to update
the DPHY timings accordingly.
--
2.39.2