Re: [PATCH v8 1/4] drm/bridge: add support for sn65dsi86 bridge driver

[Sean Paul <seanpaul@chromium.org>]

On Tue, Jun 05, 2018 at 11:10:15AM +0530, Sandeep Panda wrote:
> Add support for TI's sn65dsi86 dsi2edp bridge chip.
> The chip converts DSI transmitted signal to eDP signal,
> which is fed to the connected eDP panel.
> 
> This chip can be controlled via either i2c interface or
> dsi interface. Currently in driver all the control registers
> are being accessed through i2c interface only.
> Also as of now HPD support has not been added to bridge
> chip driver.
> 
> Changes in v1:
>  - Split the dt-bindings and the driver support into separate patches
>    (Andrzej Hajda).
>  - Use of gpiod APIs to parse and configure gpios instead of obsolete ones
>    (Andrzej Hajda).
>  - Use macros to define the register offsets (Andrzej Hajda).
> 
> Changes in v2:
>  - Separate out edp panel specific HW resource handling from bridge
>    driver and create a separate edp panel drivers to handle panel
>    specific mode information and HW resources (Sean Paul).
>  - Replace pr_* APIs to DRM_* APIs to log error or debug information
>    (Sean Paul).
>  - Remove some of the unnecessary structure/variable from driver (Sean
>    Paul).
>  - Rename the function and structure prefix "sn65dsi86" to "ti_sn_bridge"
>    (Sean Paul / Rob Herring).
>  - Remove most of the hard-coding and modified the bridge init sequence
>    based on current mode (Sean Paul).
>  - Remove the existing function to retrieve the EDID data and
>    implemented this as an i2c_adapter and use drm_get_edid() (Sean Paul).
>  - Remove the dummy irq handler implementation, will add back the
>    proper irq handling later (Sean Paul).
>  - Capture the required enable gpios in a single array based on dt entry
>    instead of having individual descriptor for each gpio (Sean Paul).
> 
> Changes in v3:
>  - Remove usage of irq_gpio and replace it as "interrupts" property (Rob
>    Herring).
>  - Remove the unnecessary header file inclusions (Sean Paul).
>  - Rearrange the header files in alphabetical order (Sean Paul).
>  - Use regmap interface to perform i2c transactions.
>  - Update Copyright/License field and address other review comments
>    (Jordan Crouse).
> 
> Changes in v4:
>  - Update License/Copyright (Sean Paul).
>  - Add Kconfig and Makefile changes (Sean Paul).
>  - Drop i2c gpio handling from this bridge driver, since i2c sda/scl gpios
>    will be handled by i2c master.
>  - Update required supplies names.
>  - Remove unnecessary goto statements (Sean Paul).
>  - Add mutex lock to power_ctrl API to avoid race conditions (Sean
>    Paul).
>  - Add support to parse reference clk frequency from dt(optional).
>  - Update the bridge chip enable/disable sequence.
> 
> Changes in v5:
>  - Fixed Kbuild test service reported warnings.
> 
> Changes in v6:
>  - Use PM runtime based ref-counting instead of local ref_count mechanism
>    (Stephen Boyd).
>  - Clean up some debug logs and indentations (Sean Paul).
>  - Simplify dp rate calculation (Sean Paul).
>  - Add support to configure refclk based on input REFCLK pin or DACP/N
>    pin (Stephen Boyd).
> 
> Changes in v7:
>  - Use static supply entries instead of dynamic allocation (Andrzej
>    Hajda).
>  - Defer bridge driver probe if panel is not probed (Andrzej Hajda).
>  - Update of_graph APIs for correct node reference management. (Andrzej
>    Hajda).
>  - Remove local display_mode object (Andrzej Hajda).
>  - Remove version id check function from driver.
> 
> Changes in v8:
>  - Move dsi register/attach function to bridge driver probe (Andrzej
>    Hajda).
>  - Introduce a new helper function to write 16bit words into consecutive
>    registers (Andrzej Hajda).
>  - Remove unnecessary macros (Andrzej Hajda).
> 
> Signed-off-by: Sandeep Panda <spanda@codeaurora.org>
> ---
>  drivers/gpu/drm/bridge/Kconfig        |   9 +
>  drivers/gpu/drm/bridge/Makefile       |   1 +
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 666 ++++++++++++++++++++++++++++++++++
>  3 files changed, 676 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/ti-sn65dsi86.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 3b99d5a..8153150 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -108,6 +108,15 @@ config DRM_TI_TFP410
>  	---help---
>  	  Texas Instruments TFP410 DVI/HDMI Transmitter driver
>  
> +config DRM_TI_SN65DSI86
> +	tristate "TI SN65DSI86 DSI to eDP bridge"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	select DRM_PANEL
> +	---help---
> +	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
> +
>  source "drivers/gpu/drm/bridge/analogix/Kconfig"
>  
>  source "drivers/gpu/drm/bridge/adv7511/Kconfig"
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 373eb28..3711be8 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -12,4 +12,5 @@ obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o

SN65DSI86 should be in front of TFP410 here and above.

>  obj-y += synopsys/
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> new file mode 100644
> index 0000000..add6e0f
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c

/snip

> +
> +#define REFCLK_LUT_SIZE	5
> +
> +/* clk frequencies supported by bridge in Hz in case derived from REFCLK pin */
> +static const u32 ti_sn_bridge_refclk_lut[] = {
> +	12000000,
> +	19200000,
> +	26000000,
> +	27000000,
> +	38400000,
> +};
> +
> +/* clk frequencies supported by bridge in Hz in case derived from DACP/N pin */
> +static const u32 ti_sn_bridge_dsiclk_lut[] = {
> +	468000000,
> +	384000000,
> +	416000000,
> +	486000000,
> +	460800000,
> +};
> +
> +static void ti_sn_bridge_set_refclk(struct ti_sn_bridge *pdata)
> +{
> +	int i = 0;
> +	u8 refclk_src;
> +	u32 refclk_rate;
> +	const u32 *refclk_lut;
> +
> +	if (pdata->refclk) {
> +		refclk_src = DPPLL_CLK_SRC_REFCLK;
> +		refclk_rate = clk_get_rate(pdata->refclk);
> +		refclk_lut = ti_sn_bridge_refclk_lut;
> +		clk_prepare_enable(pdata->refclk);
> +	} else {
> +		refclk_src = DPPLL_CLK_SRC_DSICLK;
> +		refclk_rate = ti_sn_bridge_get_dsi_freq(pdata) * 1000;
> +		refclk_lut = ti_sn_bridge_dsiclk_lut;
> +	}
> +
> +	/* for i equals to REFCLK_LUT_SIZE means default frequency */
> +	for (i = 0; i < REFCLK_LUT_SIZE; i++)

Instead of REFCLK_LUT_SIZE, use a local variable, ie:

        size_t refclk_lut_size;

        ...

        if(pdata->refclk) {
                ...
                refclk_lut = ti_sn_bridge_refclk_lut;
                refclk_lut_size = ARRAY_SIZE(ti_sn_bridge_refclk_lut);
                ...
        } else {
                ...
                refclk_lut = ti_sn_bridge_dsiclk_lut;
                refclk_lut_size = ARRAY_SIZE(ti_sn_bridge_dsiclk_lut);
        }

And remove REFCLK_LUT_SIZE.

> +		if (refclk_lut[i] == refclk_rate)
> +			break;
> +
> +	regmap_write(pdata->regmap, SN_REFCLK_FREQ_REG,
> +		     (refclk_src | (i << SN_DSIA_REFCLK_OFFSET)));
> +}
> +
> +/**
> + * LUT index corresponds to register value and
> + * LUT values corresponds to dp data rate supported
> + * by the bridge in Mbps unit.
> + */
> +static const unsigned int ti_sn_bridge_dp_rate_lut[] = {
> +	0, 1620, 2160, 2430, 2700, 3240, 4320, 5400
> +};
> +
> +static void ti_sn_bridge_set_dsi_dp_rate(struct ti_sn_bridge *pdata)
> +{
> +	unsigned int bit_rate_mhz, clk_freq_mhz, dp_rate_mhz;
> +	unsigned int val = 0, i = 0;
> +	struct drm_display_mode *mode =
> +		&pdata->bridge.encoder->crtc->state->adjusted_mode;
> +
> +	/* set DSIA clk frequency */
> +	bit_rate_mhz = (mode->clock / 1000) *
> +			mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
> +	clk_freq_mhz = bit_rate_mhz / (pdata->dsi->lanes * 2);
> +
> +	/* for each increment in val, frequency increases by 5MHz */
> +	val = (MIN_DSI_CLK_FREQ_MHZ / 5) +
> +		(((clk_freq_mhz - MIN_DSI_CLK_FREQ_MHZ) / 5) & 0xFF);
> +	regmap_write(pdata->regmap, SN_DSIA_CLK_FREQ_REG, val);
> +
> +	/* set DP data rate */
> +	dp_rate_mhz = ((bit_rate_mhz / pdata->dsi->lanes) * DP_CLK_FUDGE_NUM) /
> +							DP_CLK_FUDGE_DEN;
> +	for (i = 0; i < ARRAY_SIZE(ti_sn_bridge_dp_rate_lut) - 1; i++)
> +		if (ti_sn_bridge_dp_rate_lut[i] > dp_rate_mhz)
> +			break;
> +
> +	regmap_update_bits(pdata->regmap, SN_DATARATE_CONFIG_REG,
> +			   SN_DP_DATA_RATE_BITS, i << SN_DP_DATA_RATE_OFFSET);
> +}
> +
> +static void ti_sn_bridge_set_video_timings(struct ti_sn_bridge *pdata)
> +{
> +	struct drm_display_mode *mode =
> +		&pdata->bridge.encoder->crtc->state->adjusted_mode;
> +
> +	ti_sn_bridge_write_u16(pdata, SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG,
> +			       mode->hdisplay);
> +	ti_sn_bridge_write_u16(pdata, SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG,
> +			       mode->vdisplay);
> +	ti_sn_bridge_write_u16(pdata, SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG,
> +			       mode->hsync_end - mode->hsync_start);
> +	ti_sn_bridge_write_u16(pdata, SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG,
> +			       mode->vsync_end - mode->vsync_start);
> +
> +	regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_BACK_PORCH_REG,
> +		     (mode->htotal - mode->hsync_end) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_BACK_PORCH_REG,
> +		     (mode->vtotal - mode->vsync_end) & 0xFF);
> +
> +	regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_FRONT_PORCH_REG,
> +		     (mode->hsync_start - mode->hdisplay) & 0xFF);
> +	regmap_write(pdata->regmap, SN_CHA_VERTICAL_FRONT_PORCH_REG,
> +		     (mode->vsync_start - mode->vdisplay) & 0xFF);
> +
> +	usleep_range(10000, 10500); /* 10ms delay recommended by spec */
> +}
> +
> +static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> +	unsigned int val = 0;
> +
> +	if (pdata->panel) {
> +		drm_panel_prepare(pdata->panel);
> +		/* in case drm_panel is connected then HPD is not supported */
> +		regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
> +				   SN_HPD_DISABLE_BIT, !0);

What is !0?

Sean

/snip

-- 
Sean Paul, Software Engineer, Google / Chromium OS
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