? 2017-06-07 17:38?Maxime Ripard ???

On Mon, Jun 05, 2017 at 12:01:45AM +0800, Icenowy Zheng wrote:

quoted

Allwinner H3 features a TV encoder similar to the one in earlier SoCs,
but has a internal fixed clock divider that divides the TCON1 clock
(called TVE clock in datasheet) by 11.

Add support for it.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
---
Changes in v2:
- Quirk part rewritten.

 drivers/gpu/drm/sun4i/sun4i_tv.c | 35 
++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tv.c 

b/drivers/gpu/drm/sun4i/sun4i_tv.c
index 338b9e5bb2a3..b9ff6d5ea67a 100644

--- a/drivers/gpu/drm/sun4i/sun4i_tv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tv.c

@@ -13,6 +13,7 @@
 #include <linux/clk.h>
 #include <linux/component.h>
 #include <linux/of_address.h>
+#include <linux/of_device.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>

@@ -169,14 +170,21 @@ struct tv_mode {
 	const struct resync_parameters	*resync_params;
 };

+struct sun4i_tv_quirks {
+	int fixed_divider;
+};
+
 struct sun4i_tv {
 	struct drm_connector	connector;
 	struct drm_encoder	encoder;

 	struct clk		*clk;
+	struct clk		*mod_clk;
 	struct regmap		*regs;
 	struct reset_control	*reset;

+	const struct sun4i_tv_quirks *quirks;
+
 	struct sun4i_drv	*drv;
 };

@@ -391,6 +399,12 @@ static void sun4i_tv_mode_set(struct drm_encoder 

*encoder,
 	struct sun4i_tcon *tcon = crtc->tcon;
 	const struct tv_mode *tv_mode = sun4i_tv_find_tv_by_mode(mode);

+	if (tv->quirks->fixed_divider) {
+		DRM_DEBUG_DRIVER("Applying fixed divider %d on TVE clock\n",
+				 tv->quirks->fixed_divider);
+		mode->crtc_clock *= tv->quirks->fixed_divider;
+	}
+

You're not allowed to change the mode in mode_set, and you shouldn't
even change it. The output pixel clock is still 27MHz.

You should implement that using the states, as we discussed already.

After reading the comments at include/drm/drm_modeset_helper_vtables.h,
I think the atomic_check function is allowed to directly change
the adjust_mode of crtc_state.

And according to other comments at include/drm/drm_modes.h, the
crtc_clock in adjust_mode should be the clock to be really feed
to the hardware.

So I think I can just change this in atomic_check.

However, the mode_set function of sun4i_tv seems to be not
regarding adjusted_mode and still use original mode.

So my current design is:
- Multiply adjusted_mode in atomic_check.
- Feed adjust_mode to TCON code in mode_set function.

Is this proper?

(From my own understanding to the comments I think so.)

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel