Hi

Am 09.07.21 um 20:50 schrieb Sam Ravnborg:

Hi Thomas,

On Mon, Jul 05, 2021 at 02:45:04PM +0200, Thomas Zimmermann wrote:

...

Put the clock-selection code into each of the PLL-update functions to make them select the correct pixel clock.

The pixel clock for video output was not actually set before programming the clock's values. It worked because the device had the correct clock pre-set.

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: db05f8d3dc87 ("drm/mgag200: Split MISC register update into PLL selection, SYNC and I/O") Cc: Sam Ravnborg sam@ravnborg.org Cc: Emil Velikov emil.velikov@collabora.com Cc: Dave Airlie airlied@redhat.com Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.9+

---

drivers/gpu/drm/mgag200/mgag200_mode.c | 47 ++++++++++++++++++++------ 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index 3b3059f471c2..482843ebb69f 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -130,6 +130,7 @@ static int mgag200_g200_set_plls(struct mga_device *mdev, long clock) long ref_clk = mdev->model.g200.ref_clk; long p_clk_min = mdev->model.g200.pclk_min; long p_clk_max = mdev->model.g200.pclk_max;

• u8 misc;

if (clock > p_clk_max) { drm_err(dev, "Pixel Clock %ld too high\n", clock); @@ -174,6 +175,11 @@ static int mgag200_g200_set_plls(struct mga_device *mdev, long clock) drm_dbg_kms(dev, "clock: %ld vco: %ld m: %d n: %d p: %d s: %d\n", clock, f_vco, m, n, p, s);

• misc = RREG8(MGA_MISC_IN);
• misc &= ~MGAREG_MISC_CLK_SEL_MASK;
• misc |= MGAREG_MISC_CLK_SEL_MGA_MSK;
• WREG8(MGA_MISC_OUT, misc);

This chunk is repeated a number of times. Any good reason why this is not a small helper?

Good point. I'll make a helper from this.

Best regards Thomas

Sam