[PATCH v3 0/4] Config mipi tx drive current and impedance

[PATCH v3 0/4] Config mipi tx drive current and impedance

[Jitao Shi]

Changes since v2:
 - fix the title of commit message.
 - rename mipitx-current-drive to drive-strength-microamp

Changes since v1:
 - fix coding style.
 - change mtk_mipi_tx_config_calibration_data() to void

Jitao Shi (4):
  dt-bindings: display: mediatek: add property to control mipi tx drive
    current
  dt-bindings: display: mediatek: get mipitx calibration data from nvmem
  drm/mediatek: add the mipitx driving control
  drm/mediatek: config mipitx impedance with calibration data

 .../display/mediatek/mediatek,dsi.txt         |  9 +++
 drivers/gpu/drm/mediatek/mtk_mipi_tx.c        |  6 ++
 drivers/gpu/drm/mediatek/mtk_mipi_tx.h        |  1 +
 drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c | 64 +++++++++++++++++++
 4 files changed, 80 insertions(+)

-- 
2.21.0

[PATCH v3 1/4] dt-bindings: display: mediatek: add property to control mipi tx drive current

[Jitao Shi]

Add a property to control mipi tx drive current:
"drive-strength-microamp"

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
---
 .../devicetree/bindings/display/mediatek/mediatek,dsi.txt     | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
index a19a6cc375ed..d501f9ff4b1f 100644
--- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
+++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
@@ -33,6 +33,9 @@ Required properties:
 - #clock-cells: must be <0>;
 - #phy-cells: must be <0>.
 
+Optional properties:
+- drive-strength-microamp: adjust driving current, should be 1 ~ 0xF
+
 Example:
 
 mipi_tx0: mipi-dphy@10215000 {
@@ -42,6 +45,7 @@ mipi_tx0: mipi-dphy@10215000 {
 	clock-output-names = "mipi_tx0_pll";
 	#clock-cells = <0>;
 	#phy-cells = <0>;
+	drive-strength-microamp = <0x8>;
 };
 
 dsi0: dsi@1401b000 {
-- 
2.21.0

Re: [PATCH v3 1/4] dt-bindings: display: mediatek: add property to control mipi tx drive current

[Rob Herring]

On Wed, Mar 11, 2020 at 03:40:29PM +0800, Jitao Shi wrote:
> Add a property to control mipi tx drive current:
> "drive-strength-microamp"
> 
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> ---
>  .../devicetree/bindings/display/mediatek/mediatek,dsi.txt     | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> index a19a6cc375ed..d501f9ff4b1f 100644
> --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> @@ -33,6 +33,9 @@ Required properties:
>  - #clock-cells: must be <0>;
>  - #phy-cells: must be <0>.
>  
> +Optional properties:
> +- drive-strength-microamp: adjust driving current, should be 1 ~ 0xF

TBC, 1-0xf is in units of microamps? So a max drive strength of 15uA? 
Seems a bit low.

> +
>  Example:
>  
>  mipi_tx0: mipi-dphy@10215000 {
> @@ -42,6 +45,7 @@ mipi_tx0: mipi-dphy@10215000 {
>  	clock-output-names = "mipi_tx0_pll";
>  	#clock-cells = <0>;
>  	#phy-cells = <0>;
> +	drive-strength-microamp = <0x8>;
>  };
>  
>  dsi0: dsi@1401b000 {
> -- 
> 2.21.0

Re: [PATCH v3 1/4] dt-bindings: display: mediatek: add property to control mipi tx drive current

[Jitao Shi]

On Mon, 2020-03-23 at 16:00 -0600, Rob Herring wrote:
> On Wed, Mar 11, 2020 at 03:40:29PM +0800, Jitao Shi wrote:
> > Add a property to control mipi tx drive current:
> > "drive-strength-microamp"
> > 
> > Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> > ---
> >  .../devicetree/bindings/display/mediatek/mediatek,dsi.txt     | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> > index a19a6cc375ed..d501f9ff4b1f 100644
> > --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> > +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> > @@ -33,6 +33,9 @@ Required properties:
> >  - #clock-cells: must be <0>;
> >  - #phy-cells: must be <0>.
> >  
> > +Optional properties:
> > +- drive-strength-microamp: adjust driving current, should be 1 ~ 0xF
> 
> TBC, 1-0xf is in units of microamps? So a max drive strength of 15uA? 
> Seems a bit low.
> 

The minimum amp is 3000 macroamps,  step is 200macroamps.
So the drive current is 3000 + 200 * drive-strength-microamp amps.

I will update "drive-strength-microamp" define next version.

BR
Jitao
> > +
> >  Example:
> >  
> >  mipi_tx0: mipi-dphy@10215000 {
> > @@ -42,6 +45,7 @@ mipi_tx0: mipi-dphy@10215000 {
> >  	clock-output-names = "mipi_tx0_pll";
> >  	#clock-cells = <0>;
> >  	#phy-cells = <0>;
> > +	drive-strength-microamp = <0x8>;
> >  };
> >  
> >  dsi0: dsi@1401b000 {
> > -- 
> > 2.21.0

[PATCH v3 2/4] dt-bindings: display: mediatek: get mipitx calibration data from nvmem

[Jitao Shi]

Add properties to get get mipitx calibration data.

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
---
 .../devicetree/bindings/display/mediatek/mediatek,dsi.txt    | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
index d501f9ff4b1f..b179293c43de 100644
--- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
+++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
@@ -34,6 +34,9 @@ Required properties:
 - #phy-cells: must be <0>.
 
 Optional properties:
+- nvmem-cells: A phandle to the calibration data provided by a nvmem device. If
+               unspecified default values shall be used.
+- nvmem-cell-names: Should be "calibration-data"
 - drive-strength-microamp: adjust driving current, should be 1 ~ 0xF
 
 Example:
@@ -45,6 +48,8 @@ mipi_tx0: mipi-dphy@10215000 {
 	clock-output-names = "mipi_tx0_pll";
 	#clock-cells = <0>;
 	#phy-cells = <0>;
+	nvmem-cells= <&mipi_tx_calibration>;
+	nvmem-cell-names = "calibration-data";
 	drive-strength-microamp = <0x8>;
 };
 
-- 
2.21.0

Re: [PATCH v3 2/4] dt-bindings: display: mediatek: get mipitx calibration data from nvmem

[Rob Herring]

On Wed, 11 Mar 2020 15:40:30 +0800, Jitao Shi wrote:
> Add properties to get get mipitx calibration data.
> 
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> ---
>  .../devicetree/bindings/display/mediatek/mediatek,dsi.txt    | 5 +++++
>  1 file changed, 5 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH v3 3/4] drm/mediatek: add the mipitx driving control

[Jitao Shi]

Add a property in device tree to control the driving by different
board.

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_mipi_tx.c        | 6 ++++++
 drivers/gpu/drm/mediatek/mtk_mipi_tx.h        | 1 +
 drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c | 7 +++++++
 3 files changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_mipi_tx.c b/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
index e4d34484ecc8..2a1ac4e97cbb 100644
--- a/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
+++ b/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
@@ -125,6 +125,12 @@ static int mtk_mipi_tx_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	ret = of_property_read_u32(dev->of_node, "drive-strength-microamp",
+				   &mipi_tx->mipitx_drive);
+	/* If can't get the "mipi_tx->mipitx_drive", set it default 0x8 */
+	if (ret < 0)
+		mipi_tx->mipitx_drive = 0x8;
+
 	ref_clk_name = __clk_get_name(ref_clk);
 
 	ret = of_property_read_string(dev->of_node, "clock-output-names",
diff --git a/drivers/gpu/drm/mediatek/mtk_mipi_tx.h b/drivers/gpu/drm/mediatek/mtk_mipi_tx.h
index 413f35d86219..eea44327fe9f 100644
--- a/drivers/gpu/drm/mediatek/mtk_mipi_tx.h
+++ b/drivers/gpu/drm/mediatek/mtk_mipi_tx.h
@@ -27,6 +27,7 @@ struct mtk_mipi_tx {
 	struct device *dev;
 	void __iomem *regs;
 	u32 data_rate;
+	u32 mipitx_drive;
 	const struct mtk_mipitx_data *driver_data;
 	struct clk_hw pll_hw;
 	struct clk *pll;
diff --git a/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c b/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
index 91f08a351fd0..124fdf95f1e5 100644
--- a/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
+++ b/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
@@ -17,6 +17,9 @@
 #define RG_DSI_BG_CORE_EN		BIT(7)
 #define RG_DSI_PAD_TIEL_SEL		BIT(8)
 
+#define MIPITX_VOLTAGE_SEL	0x0010
+#define RG_DSI_HSTX_LDO_REF_SEL		(0xf << 6)
+
 #define MIPITX_PLL_PWR		0x0028
 #define MIPITX_PLL_CON0		0x002c
 #define MIPITX_PLL_CON1		0x0030
@@ -123,6 +126,10 @@ static void mtk_mipi_tx_power_on_signal(struct phy *phy)
 	mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_D3_SW_CTL_EN, DSI_SW_CTL_EN);
 	mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_CK_SW_CTL_EN, DSI_SW_CTL_EN);
 
+	mtk_mipi_tx_update_bits(mipi_tx, MIPITX_VOLTAGE_SEL,
+				RG_DSI_HSTX_LDO_REF_SEL,
+				mipi_tx->mipitx_drive << 6);
+
 	mtk_mipi_tx_set_bits(mipi_tx, MIPITX_CK_CKMODE_EN, DSI_CK_CKMODE_EN);
 }
 
-- 
2.21.0

[PATCH v3 4/4] drm/mediatek: config mipitx impedance with calibration data

[Jitao Shi]

Read calibration data from nvmem, and config mipitx impedance with
calibration data to make sure their impedance are 100ohm.

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c b/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
index 124fdf95f1e5..878feeb7ac6c 100644
--- a/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
+++ b/drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
@@ -5,6 +5,8 @@
  */
 
 #include "mtk_mipi_tx.h"
+#include <linux/nvmem-consumer.h>
+#include <linux/slab.h>
 
 #define MIPITX_LANE_CON		0x000c
 #define RG_DSI_CPHY_T1DRV_EN		BIT(0)
@@ -28,6 +30,7 @@
 #define MIPITX_PLL_CON4		0x003c
 #define RG_DSI_PLL_IBIAS		(3 << 10)
 
+#define MIPITX_D2P_RTCODE	0x0100
 #define MIPITX_D2_SW_CTL_EN	0x0144
 #define MIPITX_D0_SW_CTL_EN	0x0244
 #define MIPITX_CK_CKMODE_EN	0x0328
@@ -108,6 +111,58 @@ static const struct clk_ops mtk_mipi_tx_pll_ops = {
 	.recalc_rate = mtk_mipi_tx_pll_recalc_rate,
 };
 
+static void mtk_mipi_tx_config_calibration_data(struct mtk_mipi_tx *mipi_tx)
+{
+	u32 *buf;
+	u32 rt_code[5];
+	int i, j;
+	struct nvmem_cell *cell;
+	struct device *dev = mipi_tx->dev;
+	size_t len;
+
+	cell = nvmem_cell_get(dev, "calibration-data");
+	if (IS_ERR(cell)) {
+		dev_info(dev, "nvmem_cell_get fail\n");
+		return;
+	}
+
+	buf = (u32 *)nvmem_cell_read(cell, &len);
+
+	nvmem_cell_put(cell);
+
+	if (IS_ERR(buf)) {
+		dev_info(dev, "can't get data\n");
+		return;
+	}
+
+	if (len < 3 * sizeof(u32)) {
+		dev_info(dev, "invalid calibration data\n");
+		kfree(buf);
+		return;
+	}
+
+	rt_code[0] = ((buf[0] >> 6 & 0x1f) << 5) | (buf[0] >> 11 & 0x1f);
+	rt_code[1] = ((buf[1] >> 27 & 0x1f) << 5) | (buf[0] >> 1 & 0x1f);
+	rt_code[2] = ((buf[1] >> 17 & 0x1f) << 5) | (buf[1] >> 22 & 0x1f);
+	rt_code[3] = ((buf[1] >> 7 & 0x1f) << 5) | (buf[1] >> 12 & 0x1f);
+	rt_code[4] = ((buf[2] >> 27 & 0x1f) << 5) | (buf[1] >> 2 & 0x1f);
+
+	for (i = 0; i < 5; i++) {
+		if ((rt_code[i] & 0x1f) == 0)
+			rt_code[i] |= 0x10;
+
+		if ((rt_code[i] >> 5 & 0x1f) == 0)
+			rt_code[i] |= 0x10 << 5;
+
+		for (j = 0; j < 10; j++)
+			mtk_mipi_tx_update_bits(mipi_tx,
+				MIPITX_D2P_RTCODE * (i + 1) + j * 4,
+				1, rt_code[i] >> j & 1);
+	}
+
+	kfree(buf);
+}
+
 static void mtk_mipi_tx_power_on_signal(struct phy *phy)
 {
 	struct mtk_mipi_tx *mipi_tx = phy_get_drvdata(phy);
@@ -130,6 +185,8 @@ static void mtk_mipi_tx_power_on_signal(struct phy *phy)
 				RG_DSI_HSTX_LDO_REF_SEL,
 				mipi_tx->mipitx_drive << 6);
 
+	mtk_mipi_tx_config_calibration_data(mipi_tx);
+
 	mtk_mipi_tx_set_bits(mipi_tx, MIPITX_CK_CKMODE_EN, DSI_CK_CKMODE_EN);
 }
 
-- 
2.21.0