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Date: Tue, 12 Jul 2016 16:27:40 +0200
From: Heiko Stübner <heiko@...ech.de>
To: Yakir Yang <ykk@...k-chips.com>
Cc: Mark Yao <mark.yao@...k-chips.com>,
Rob Herring <robh+dt@...nel.org>,
Russell King <rmk+kernel@....linux.org.uk>,
Philipp Zabel <p.zabel@...gutronix.de>,
Andy Yan <andy.yan@...k-chips.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Kumar Gala <galak@...eaurora.org>,
Zheng Yang <zhengyang@...k-chips.com>, xhc@...k-chips.com,
dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 5/6] drm/rockchip: dw_hdmi: introduce the VPLL clock setting
Hi Yakir,
Am Montag, 11. Juli 2016, 19:05:49 schrieb Yakir Yang:
> For RK3399 HDMI, there is an external clock need for HDMI PHY,
> and it should keep the same clock rate with VOP DCLK.
>
> VPLL have supported the clock for HDMI PHY, but there is no
> clock divider bewteen VPLL and HDMI PHY. So we need to set the
> VPLL rate manually in HDMI driver.
I don't think reserving the vpll for the hdmi at all times is the right way to
go.
While I do agree that reserving the VPLL (and NPLL on the rk3288) for graphics
use looks like the right way, I think the core Rockchip drm driver should be
responsible for managing it and also for deciding which output encoder gets to
use it.
While true that on the Chromebook device-types the edp is static and hdmi
needs the broad range of dynamic frequencies, this is not necessarily the case
for all future device types and/or socs.
In the other thread we discussed adding that as rockchip,dclk-pll = <&...>; to
the base display-subsystem node, Doug didn't manage to find time to respond yet
though - and is on vacation right now.
I still believe that would be the best solution :-) .
That property could list 1 or even 2 plls, depending on the soc or board
layout - maybe someone frees up the cpll in some special layout or something.
If none are listed, then the drm driver would need to cope with its available
clocks.
Implementation-wise you could even still keep your shortcut until we encounter
a device with different , let the drm use the pll for hdmi only until someone
comes up with a better concept, but still the binding should be correct and
versatile from the start.
Heiko
> ---
> .../bindings/display/rockchip/dw_hdmi-rockchip.txt | 3 ++-
> drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 25
> +++++++++++++++++++++- 2 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git
> a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> b/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> index 4e573d2..4e23ca4 100644
> ---
> a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> +++
> b/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> @@ -17,7 +17,8 @@ Required properties:
>
> Optional properties
> - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
> -- clocks, clock-names: phandle to the HDMI CEC clock, name should be "cec"
> +- clocks, clock-names: phandle to the HDMI CEC clock, name should be "cec",
> + phandle to the VPLL clock, name should be "vpll".
>
> Example:
> hdmi: hdmi@...80000 {
> diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c index 329099b..701bb73 100644
> --- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> @@ -7,10 +7,12 @@
> * (at your option) any later version.
> */
>
> +#include <linux/clk.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
> -#include <linux/mfd/syscon.h>
> #include <linux/regmap.h>
> +
> #include <drm/drm_of.h>
> #include <drm/drmP.h>
> #include <drm/drm_crtc_helper.h>
> @@ -33,6 +35,7 @@ struct rockchip_hdmi {
> struct regmap *regmap;
> struct drm_encoder encoder;
> enum dw_hdmi_devtype dev_type;
> + struct clk *vpll_clk;
> };
>
> #define to_rockchip_hdmi(x) container_of(x, struct rockchip_hdmi, x)
> @@ -145,6 +148,7 @@ static const struct dw_hdmi_phy_config
> rockchip_phy_config[] = { static int rockchip_hdmi_parse_dt(struct
> rockchip_hdmi *hdmi)
> {
> struct device_node *np = hdmi->dev->of_node;
> + int ret;
>
> hdmi->regmap = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
> if (IS_ERR(hdmi->regmap)) {
> @@ -152,6 +156,22 @@ static int rockchip_hdmi_parse_dt(struct rockchip_hdmi
> *hdmi) return PTR_ERR(hdmi->regmap);
> }
>
> + hdmi->vpll_clk = devm_clk_get(hdmi->dev, "vpll");
> + if (PTR_ERR(hdmi->vpll_clk) == -ENOENT) {
> + hdmi->vpll_clk = NULL;
> + } else if (PTR_ERR(hdmi->vpll_clk) == -EPROBE_DEFER) {
> + return -EPROBE_DEFER;
> + } else if (IS_ERR(hdmi->vpll_clk)) {
> + dev_err(hdmi->dev, "failed to get grf clock\n");
> + return PTR_ERR(hdmi->vpll_clk);
> + }
> +
> + ret = clk_prepare_enable(hdmi->vpll_clk);
> + if (ret) {
> + dev_err(hdmi->dev, "Failed to enable HDMI vpll: %d\n", ret);
> + return ret;
> + }
> +
> return 0;
> }
>
> @@ -194,6 +214,9 @@ static void dw_hdmi_rockchip_encoder_mode_set(struct
> drm_encoder *encoder, struct drm_display_mode *mode,
> struct drm_display_mode *adj_mode)
> {
> + struct rockchip_hdmi *hdmi = to_rockchip_hdmi(encoder);
> +
> + clk_set_rate(hdmi->vpll_clk, adj_mode->clock * 1000);
> }
>
> static void dw_hdmi_rockchip_encoder_enable(struct drm_encoder *encoder)
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