With display pixel clocks we want to have the closest possible clock
rate, to minimize timing and refresh rate skews. Whether the actual
clock rate is higher or lower than the requested rate is less important.
Also check candidates against the requested rate, rather than the
ideal parent rate, the varying dividers also influence the difference
between the requested rate and the rounded rate.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
The dot clock divider is 7 bits wide, and the divider range is 1 ~ 127,
or 6 ~ 127 if phase offsets are used. The 0 register value also
represents a divider of 1 or bypass.
Make the end condition of the for loop inclusive of 127 in the
round_rate callback.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
When reading back the divider set in the register, we mask off the
bits that aren't part of the divider. Unfortunately the mask used
here was not converted from the field width.
Fix this by converting the field width to a proper bit mask.
Fixes: 9026e0d122 ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
We get 5 warnings when building kernel with W=1:
drivers/gpu/drm/sun4i/sun4i_framebuffer.c:33:23: warning: no previous prototype for 'sun4i_framebuffer_init' [-Wmissing-prototypes]
drivers/gpu/drm/sun4i/sun4i_framebuffer.c:47:6: warning: no previous prototype for 'sun4i_framebuffer_free' [-Wmissing-prototypes]
drivers/gpu/drm/sun4i/sun4i_rgb.c:202:5: warning: no previous prototype for 'sun4i_rgb_init' [-Wmissing-prototypes]
drivers/gpu/drm/sun4i/sun4i_dotclock.c:151:5: warning: no previous prototype for 'sun4i_dclk_create' [-Wmissing-prototypes]
drivers/gpu/drm/sun4i/sun4i_dotclock.c:186:5: warning: no previous prototype for 'sun4i_dclk_free' [-Wmissing-prototypes]
In fact, these functions are declared in
drivers/gpu/drm/sun4i/sun4i_framebuffer.h,
drivers/gpu/drm/sun4i/sun4i_rgb.h,
drivers/gpu/drm/sun4i/sun4i_dotclock.h,
so this patch adds missing header dependencies.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Our pixel clock currently only tries to deal with the current parent rate.
While that works when the resolution is the same than the one already
program, or when we can compute directly the rate from the current parent
rate, it cannot work in most situation when we want to change the
frequency, and we end up with an improper pixel clock rate, which obviously
doesn't work as expected.
Ask our parent for all the possible dividers if it can reach that
frequency, and return the best parent rate to the clock framework so that
we can use it.
Fixes: 9026e0d122 ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
gcc points out a possible uninitialized variable use in
sun4i_dclk_create():
drivers/gpu/drm/sun4i/sun4i_dotclock.c: In function 'sun4i_dclk_create':
drivers/gpu/drm/sun4i/sun4i_dotclock.c:139:12: error: 'clk_name' may be used uninitialized in this function [-Werror=maybe-uninitialized]
init.name = clk_name;
The warning only shows up when CONFIG_OF is disabled, and the
property is never filled, but the same bug can show up even
when CONFIG_OF is enabled but of_property_read_string_index
returns another error.
To fix it, this ensures that sun4i_dclk_create propagates
any error from of_property_read_string_index.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 9026e0d122 ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
The Allwinner A10 and subsequent SoCs share the same display pipeline, with
variations in the number of controllers (1 or 2), or the presence or not of
some output (HDMI, TV, VGA) or not.
Add a driver with a limited set of features for now, and we will hopefully
support all of them eventually
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
