Re: [PATCH RFC v2 08/14] drm: imx: Add MIPI DSI host controller driver
From: Liu Ying
Date: Fri Dec 19 2014 - 00:49:15 EST
On 12/18/2014 07:39 PM, Philipp Zabel wrote:
Am Donnerstag, den 18.12.2014, 15:11 +0800 schrieb Liu Ying:
This patch adds i.MX MIPI DSI host controller driver support.
Currently, the driver supports the burst with sync pulses mode only.
Signed-off-by: Liu Ying <Ying.Liu@xxxxxxxxxxxxx>
---
v1->v2:
* Address almost all comments from Thierry Reding and Russell.
* Update the DT documentation to remove the display-timings node in the panel node.
* Update the DT documentation to state that the nodes which represent the possible
DRM CRTCs the controller may connect with should be placed in the node "ports".
* Remove the flag 'enabled' from the struct imx_mipi_dsi.
* Move the format_to_bpp() function in v1 to the common DRM MIPI DSI driver.
* Improve the way we wait for check status for DPHY and command packet transfer.
* Improve the DPMS support for the encoder.
* Split the functions of ->host_attach() and ->mode_valid() clearly as suggested by
Thierry Reding.
* Improve the logics in imx_mipi_dsi_dcs_long_write().
* Enable/disable the pllref_clk and pllref_gate_clk at the component binding/unbinding
stages to help remove the flag 'enabled'.
* Update the module license to be "GPL".
* Other minor changes, such as coding style issues and macro naming issues.
.../devicetree/bindings/drm/imx/mipi_dsi.txt | 78 ++
drivers/gpu/drm/imx/Kconfig | 6 +
drivers/gpu/drm/imx/Makefile | 1 +
drivers/gpu/drm/imx/imx-mipi-dsi.c | 1056 ++++++++++++++++++++
4 files changed, 1141 insertions(+)
create mode 100644 Documentation/devicetree/bindings/drm/imx/mipi_dsi.txt
create mode 100644 drivers/gpu/drm/imx/imx-mipi-dsi.c
diff --git a/Documentation/devicetree/bindings/drm/imx/mipi_dsi.txt b/Documentation/devicetree/bindings/drm/imx/mipi_dsi.txt
new file mode 100644
index 0000000..892ed62
--- /dev/null
+++ b/Documentation/devicetree/bindings/drm/imx/mipi_dsi.txt
@@ -0,0 +1,78 @@
+Device-Tree bindings for MIPI DSI host controller
+
+MIPI DSI host controller
+========================
+
+The MIPI DSI host controller is a Synopsys DesignWare IP.
+It is a digital core that implements all protocol functions defined
+in the MIPI DSI specification, providing an interface between the
+system and the MIPI DPHY, and allowing communication with a MIPI DSI
+compliant display.
+
+Required properties:
+ - #address-cells: Should be <1>.
+ - #size-cells: Should be <0>.
+ - compatible: Should be "fsl,imx6q-mipi-dsi" for i.MX6q/sdl SoCs.
If this is a Synopsys DesignWare IP core as the HDMI TX, I think the
compatible should reflect that. How about a second compatible
"snps,dw-mipi-dsi"?
Ok, I'll add this second compatible string.
+ - reg: Physical base address of the controller and length of memory
+ mapped region.
+ - interrupts: The controller's interrupt number to the CPU(s).
+ - gpr: Should be <&gpr>.
+ The phandle points to the iomuxc-gpr region containing the
+ multiplexer control register for the controller.
+ - clocks, clock-names: Phandles to the controller pllref, pllref_gate
+ and core_cfg clocks, as described in [1] and [2].
+
+Required sub-nodes:
+ - ports: This node may contain up to four port nodes with endpoint
+ definitions as defined in [3], corresponding to the four inputs to
+ the controller multiplexer.
+ - A node to represent a DSI peripheral as described in [4].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/clock/imx6q-clock.txt
+[3] Documentation/devicetree/bindings/media/video-interfaces.txt
+[4] Documentation/devicetree/bindings/mipi/dsi/mipi-dsi-bus.txt
+
+example:
+ gpr: iomuxc-gpr@020e0000 {
+ /* ... */
+ };
+
+ mipi_dsi: mipi@021e0000 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ compatible = "fsl,imx6q-mipi-dsi";
+ reg = <0x021e0000 0x4000>;
+ interrupts = <0 102 IRQ_TYPE_LEVEL_HIGH>;
+ gpr = <&gpr>;
+ clocks = <&clks IMX6QDL_CLK_VIDEO_27M>,
+ <&clks IMX6QDL_CLK_HSI_TX>,
+ <&clks IMX6QDL_CLK_HSI_TX>;
+ clock-names = "pllref", "pllref_gate", "core_cfg";
Not sure about this. Are those names from the Synopsys documentation?
No, I don't think it's from there.
According to Table 41-1 in the i.MX6Q Reference Manual, this module has
6 clock inputs:
- ac_clk_125m (from ahb_clk_root)
- pixel_clk (from axi_clk_root)
- cfg_clk and pll_refclk (from video_27m)
- ips_clk and ipg_clk_s (from ipg_clk_root)
The CCM chapter says that of these, "ac_clk_125m", "cfg_clk", ips_clk",
and "pll_refclk" are gated by a single bit called
"mipi_core_cfg_clk_enable", that is clk[CLK_HSI_TX].
If that is correct, I see no reason for the "pllref_gate" clock.
I suppose two clocks "pllref" and "cfg" should suffice.
Using the two clocks makes the code look like this, perhaps:
clocks = <&clks IMX6QDL_CLK_VIDEO_27M>,
<&clks IMX6QDL_CLK_HSI_TX>;
clock-names = "pllref", "core_cfg";
Then, it seems that I have no way to disable the pllref clock if
using the clock tree after applying this patch set?
Or, perhaps, this one?
clocks = <&clks IMX6QDL_CLK_HSI_TX>,
<&clks IMX6QDL_CLK_HSI_TX>;
clock-names = "pllref", "core_cfg";
This only uses the gate clock hsi_tx. The current clock tree states
that it comes from:
pll3_120m ->
| -> hsi_tx_sel -> hsi_tx_podf -> hsi_tx
pll2_pfd2_396m ->
So, I can not get the correct pllref clock frequency with this tree.
The pllref clock should be derived from the video_27m clock.
The way I decided to use the three clocks is:
1) PLL related
* pllref clock only cares about the pll reference rate(the frequency).
And, the frequency does matter as it has an impact on the lane clock
frequency.
* pllref_gate is a gate clock and it only cares about the gate.
2) register configuration related
* core_cfg is a gate clock and it only cares about the gate.
Usually, the register configuration clock frequency is not so important
and the gate is what we really need.
I am currently not strong on the way I used. I am open to any better
solution.
Maybe HSI_TX should be split up into multiple shared gate clocks that
all set the mipi_core_cfg clock bits (see below).
Yes, maybe.
If that's the case, do we need to add two gate clocks in the DT node to
represent cfg_gate and pllref_gate respectively?
diff --git a/drivers/gpu/drm/imx/Kconfig b/drivers/gpu/drm/imx/Kconfig
index 82fb758..03f04fb 100644
--- a/drivers/gpu/drm/imx/Kconfig
+++ b/drivers/gpu/drm/imx/Kconfig
@@ -51,3 +51,9 @@ config DRM_IMX_HDMI
depends on DRM_IMX
help
Choose this if you want to use HDMI on i.MX6.
+
+config DRM_IMX_MIPI_DSI
+ tristate "Freescale i.MX DRM MIPI DSI"
+ depends on DRM_IMX && MFD_SYSCON
+ help
+ Choose this if you want to use MIPI DSI on i.MX6.
diff --git a/drivers/gpu/drm/imx/Makefile b/drivers/gpu/drm/imx/Makefile
index 582c438..4571d52 100644
--- a/drivers/gpu/drm/imx/Makefile
+++ b/drivers/gpu/drm/imx/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_DRM_IMX_LDB) += imx-ldb.o
imx-ipuv3-crtc-objs := ipuv3-crtc.o ipuv3-plane.o
obj-$(CONFIG_DRM_IMX_IPUV3) += imx-ipuv3-crtc.o
obj-$(CONFIG_DRM_IMX_HDMI) += imx-hdmi.o
+obj-$(CONFIG_DRM_IMX_MIPI_DSI) += imx-mipi-dsi.o
diff --git a/drivers/gpu/drm/imx/imx-mipi-dsi.c b/drivers/gpu/drm/imx/imx-mipi-dsi.c
new file mode 100644
index 0000000..1cb4328
--- /dev/null
+++ b/drivers/gpu/drm/imx/imx-mipi-dsi.c
[...]
+static int imx_mipi_dsi_bind(struct device *dev, struct device *master, void *data)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct drm_device *drm = data;
+ struct device_node *np = dev->of_node;
+ struct imx_mipi_dsi *dsi;
+ struct resource *res;
+ u32 val;
+ int ret;
+
+ dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
+ if (!dsi)
+ return -ENOMEM;
+
+ dsi->dev = dev;
+ dsi->dsi_host.ops = &imx_mipi_dsi_host_ops;
+ dsi->dsi_host.dev = dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ dsi->base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(dsi->base))
+ return PTR_ERR(dsi->base);
+
+ dsi->regmap = syscon_regmap_lookup_by_phandle(np, "gpr");
+ if (IS_ERR(dsi->regmap))
+ return PTR_ERR(dsi->regmap);
+
+ dsi->pllref_clk = devm_clk_get(dev, "pllref");
+ if (IS_ERR(dsi->pllref_clk)) {
+ ret = PTR_ERR(dsi->pllref_clk);
+ dev_err(dev, "Unable to get pll reference clock: %d\n", ret);
+ return ret;
+ }
+ clk_prepare_enable(dsi->pllref_clk);
+
+ dsi->pllref_gate_clk = devm_clk_get(dev, "pllref_gate");
+ if (IS_ERR(dsi->pllref_gate_clk)) {
+ ret = PTR_ERR(dsi->pllref_gate_clk);
+ dev_err(dev, "Unable to get pll reference gate clock: %d\n", ret);
+ return ret;
+ }
+ clk_prepare_enable(dsi->pllref_gate_clk);
As said above, I don't think this clock is needed, or is it?
Perhaps, we need it.
If enabling pllref_clk doesn't actually enable the 27m clock input to
the mipi dsi core because it is still gated by hsi_tx, maybe the clock
tree should be fixed and hsi_tx turned into multiple
imx_clk_gate2_shared clocks.
According to the CCM chapter, the video_27m clock is gated by the hsi_tx
clock. You mentioned this above, as well.
+
+ dsi->cfg_clk = devm_clk_get(dev, "core_cfg");
+ if (IS_ERR(dsi->cfg_clk)) {
+ ret = PTR_ERR(dsi->cfg_clk);
+ dev_err(dev, "Unable to get configuration clock: %d\n", ret);
And leave pllref enabled?
As I mentioned in the v1-> v2 change log, I enable/disable the
pllref_clk and pllref_gate_clk at the component binding/unbinding stages
to help remove the flag 'enabled' introduced in v1.
I referred to the i.MX HDMI driver which enables/disables the isfr clock
and the iahb clock at the component binding/unbinding stages.
I may try to handle the clock enablement/disablement more decently and
avoid using the flag 'enable'.
+ return ret;
+ }
+
+ clk_prepare_enable(dsi->cfg_clk);
+ val = dsi_read(dsi, DSI_VERSION);
+ clk_disable_unprepare(dsi->cfg_clk);
+
+ dev_info(dev, "version number is 0x%08x\n", val);
+
+ ret = imx_mipi_dsi_register(drm, dsi);
+ if (ret)
Same here.
You meant that the pllref_gate clock is left enabled above, right?
Regards,
Liu Ying
+ return ret;
+
+ dev_set_drvdata(dev, dsi);
+
+ return mipi_dsi_host_register(&dsi->dsi_host);
+}
[...]
regards
Philipp
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