Message-ID: <3d3593cc-ce8d-c8da-6f41-ae7cba688a35@baylibre.com>
Date:   Fri, 20 Jan 2017 16:12:36 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     dri-devel@...ts.freedesktop.org,
        laurent.pinchart+renesas@...asonboard.com, Jose.Abreu@...opsys.com,
        kieran.bingham@...asonboard.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: Re: [RFC/RFT PATCH 1/4] drm/bridge: dw-hdmi: Switch to regmap for
 register access

On 01/17/2017 03:39 PM, Laurent Pinchart wrote:
> Hi Neil,
> 
> Thank you for the patch.
> 
> On Tuesday 17 Jan 2017 13:31:31 Neil Armstrong wrote:
>> The Synopsys Designware HDMI TX Controller does not enforce register access
>> on platforms instanciating it.
>> The current driver supports two different types of memory-mapped flat
>> register access, but in order to support the Amlogic Meson SoCs integration,
>> and provide a more generic way to handle all sorts of register mapping,
>> switch the register access to use the regmap infrastructure.
>>
>> In the case of the registers are not flat memory-mapped or does not conform
> 
> s/does/do/
> 
>> at the actual driver implementation, a regmap struct can be given in the
> 
> s/at the actual/to the current/ ?
> 
>> plat_data and be used at probe or bind.
>>
>> Since the AHB audio driver only uses direct memory access, using regmap only
>> allows the I2S audio driver to be registered.
> 
> This sounds a bit unclear to me, how about "[...], only allow the I2C audio 
> driver to be registered if the device is directly memory-mapped." ?
> 
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  drivers/gpu/drm/bridge/dw-hdmi.c | 105 +++++++++++++++++++-----------------
>>  include/drm/bridge/dw_hdmi.h     |   1 +
>>  2 files changed, 57 insertions(+), 49 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c
>> b/drivers/gpu/drm/bridge/dw-hdmi.c index ca9d0ce..13747fe 100644
>> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
>> @@ -20,6 +20,7 @@
>>  #include <linux/mutex.h>
>>  #include <linux/of_device.h>
>>  #include <linux/spinlock.h>
>> +#include <linux/regmap.h>
> 
> Could you please keep the headers alphabetically sorted ?
> 
>>  #include <drm/drm_of.h>
>>  #include <drm/drmP.h>
>> @@ -167,8 +168,7 @@ struct dw_hdmi {
>>  	unsigned int audio_n;
>>  	bool audio_enable;
>>
>> -	void (*write)(struct dw_hdmi *hdmi, u8 val, int offset);
>> -	u8 (*read)(struct dw_hdmi *hdmi, int offset);
>> +	struct regmap *regm;
>>  };
>>
>>  #define HDMI_IH_PHY_STAT0_RX_SENSE \
>> @@ -179,42 +179,23 @@ struct dw_hdmi {
>>  	(HDMI_PHY_RX_SENSE0 | HDMI_PHY_RX_SENSE1 | \
>>  	 HDMI_PHY_RX_SENSE2 | HDMI_PHY_RX_SENSE3)
>>
>> -static void dw_hdmi_writel(struct dw_hdmi *hdmi, u8 val, int offset)
>> -{
>> -	writel(val, hdmi->regs + (offset << 2));
>> -}
>> -
>> -static u8 dw_hdmi_readl(struct dw_hdmi *hdmi, int offset)
>> -{
>> -	return readl(hdmi->regs + (offset << 2));
>> -}
>> -
>> -static void dw_hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
>> -{
>> -	writeb(val, hdmi->regs + offset);
>> -}
>> -
>> -static u8 dw_hdmi_readb(struct dw_hdmi *hdmi, int offset)
>> -{
>> -	return readb(hdmi->regs + offset);
>> -}
>> -
>>  static inline void hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
> 
> Not related to this patch, but the value, offset order of arguments to the 
> write function has been making me cringe since the very first time I read the 
> code. I wonder if modifying this would be accepted.
> 
>>  {
>> -	hdmi->write(hdmi, val, offset);
>> +	regmap_write(hdmi->regm, offset, val);
>>  }
>>
>>  static inline u8 hdmi_readb(struct dw_hdmi *hdmi, int offset)
>>  {
>> -	return hdmi->read(hdmi, offset);
>> +	unsigned int val = 0;
>> +
>> +	regmap_read(hdmi->regm, offset, &val);
>> +
>> +	return val;
>>  }
>>
>>  static void hdmi_modb(struct dw_hdmi *hdmi, u8 data, u8 mask, unsigned reg)
>> {
>> -	u8 val = hdmi_readb(hdmi, reg) & ~mask;
>> -
>> -	val |= data & mask;
>> -	hdmi_writeb(hdmi, val, reg);
>> +	regmap_update_bits(hdmi->regm, reg, mask, data);
>>  }
>>
>>  static void hdmi_mask_writeb(struct dw_hdmi *hdmi, u8 data, unsigned int
>> reg, @@ -1949,6 +1930,21 @@ static int dw_hdmi_detect_phy(struct dw_hdmi
>> *hdmi) return 0;
>>  }
>>
>> +static struct regmap_config hdmi_regmap_8bit_config = {
>> +	.reg_bits	= 32,
>> +	.val_bits	= 8,
>> +	.reg_stride	= 1,
>> +	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR,
>> +};
>> +
>> +static struct regmap_config hdmi_regmap_32bit_config = {
>> +	.reg_bits	= 8,
>> +	.pad_bits	= 24,
>> +	.val_bits	= 32,
>> +	.reg_stride	= 4,
>> +	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR,
>> +};
> 
> I believe you can make these const.
> 
>>  static struct dw_hdmi *
>>  __dw_hdmi_probe(struct platform_device *pdev,
>>  		const struct dw_hdmi_plat_data *plat_data)
>> @@ -1958,7 +1954,8 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  	struct platform_device_info pdevinfo;
>>  	struct device_node *ddc_node;
>>  	struct dw_hdmi *hdmi;
>> -	struct resource *iores;
>> +	struct regmap_config *reg_config = &hdmi_regmap_8bit_config;
> 
> No need to assign a value at declaration time (unless the compiler is not 
> smart enough and complains, or is smarter than me and finds a problem where I 
> don't).
> 
>> +	struct resource *iores = NULL;
>>  	int irq;
>>  	int ret;
>>  	u32 val = 1;
>> @@ -1982,20 +1979,21 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  	mutex_init(&hdmi->audio_mutex);
>>  	spin_lock_init(&hdmi->audio_lock);
>>
>> -	of_property_read_u32(np, "reg-io-width", &val);
>> -
>> -	switch (val) {
>> -	case 4:
>> -		hdmi->write = dw_hdmi_writel;
>> -		hdmi->read = dw_hdmi_readl;
>> -		break;
>> -	case 1:
>> -		hdmi->write = dw_hdmi_writeb;
>> -		hdmi->read = dw_hdmi_readb;
>> -		break;
>> -	default:
>> -		dev_err(dev, "reg-io-width must be 1 or 4\n");
>> -		return ERR_PTR(-EINVAL);
>> +	if (plat_data->regm)
>> +		hdmi->regm = plat_data->regm;
> 
> You need curly braces around this statement.
> 
>> +	else {
>> +		of_property_read_u32(np, "reg-io-width", &val);
>> +		switch (val) {
>> +		case 4:
>> +			reg_config = &hdmi_regmap_32bit_config;
>> +			break;
>> +		case 1:
>> +			reg_config = &hdmi_regmap_8bit_config;
>> +			break;
>> +		default:
>> +			dev_err(dev, "reg-io-width must be 1 or 4\n");
>> +			return ERR_PTR(-EINVAL);
>> +		}
>>  	}
>>
>>  	ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
>> @@ -2011,11 +2009,20 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  		dev_dbg(hdmi->dev, "no ddc property found\n");
>>  	}
>>
>> -	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> -	hdmi->regs = devm_ioremap_resource(dev, iores);
>> -	if (IS_ERR(hdmi->regs)) {
>> -		ret = PTR_ERR(hdmi->regs);
>> -		goto err_res;
>> +	if (!plat_data->regm) {
>> +		iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +		hdmi->regs = devm_ioremap_resource(dev, iores);
>> +		if (IS_ERR(hdmi->regs)) {
>> +			ret = PTR_ERR(hdmi->regs);
>> +			goto err_res;
>> +		}
>> +
>> +		hdmi->regm = devm_regmap_init_mmio(dev, hdmi->regs, 
> reg_config);
>> +		if (IS_ERR(hdmi->regm)) {
>> +			dev_err(dev, "Failed to configure regmap\n");
>> +			ret = PTR_ERR(hdmi->regm);
>> +			goto err_res;
>> +		}
>>  	}
>>
>>  	hdmi->isfr_clk = devm_clk_get(hdmi->dev, "isfr");
>> @@ -2123,7 +2130,7 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  	config0 = hdmi_readb(hdmi, HDMI_CONFIG0_ID);
>>  	config3 = hdmi_readb(hdmi, HDMI_CONFIG3_ID);
>>
>> -	if (config3 & HDMI_CONFIG3_AHBAUDDMA) {
>> +	if (iores && config3 & HDMI_CONFIG3_AHBAUDDMA) {
> 
> You test !plat->regm above, and iores here. How about standardizing that ? If 
> you test for !plat->regm here, you won't have to initialize iores to NULL.
> 
> Apart from these small issues the patch looks good to me.
> 
>>  		struct dw_hdmi_audio_data audio;
>>
>>  		audio.phys = iores->start;
>> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
>> index 735a8ab..163842d 100644
>> --- a/include/drm/bridge/dw_hdmi.h
>> +++ b/include/drm/bridge/dw_hdmi.h
>> @@ -60,6 +60,7 @@ struct dw_hdmi_plat_data {
>>  			     unsigned long mpixelclock);
>>  	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
>>  					   struct drm_display_mode *mode);
>> +	struct regmap *regm;
>>  };
>>
>>  int dw_hdmi_probe(struct platform_device *pdev,
> 

Hi All,

The actual 4bytes regmap config actually fails on rk3288 because regmap bypasses
all modification of the reg address because of the regmap_mmio implementation.

The only remaining way is to keep a reg_shift in in the hdmi context, see the
patch below.

With such change, on rk3288 :
Tested-by: Neil Armstrong <narmstrong@...libre.com>

"
[   10.400294] dwhdmi-rockchip ff980000.hdmi: Detected HDMI TX controller v2.00a with HDCP (DWC MHL PHY)
"

Neil

-><------------------
diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index 8b35df5..563647f 100644
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -168,6 +168,7 @@ struct dw_hdmi {
 	unsigned int audio_n;
 	bool audio_enable;

+	unsigned int reg_shift;
 	struct regmap *regm;
 };

@@ -181,21 +182,21 @@ struct dw_hdmi {

 static inline void hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
 {
-	regmap_write(hdmi->regm, offset, val);
+	regmap_write(hdmi->regm, offset << hdmi->reg_shift, val);
 }

 static inline u8 hdmi_readb(struct dw_hdmi *hdmi, int offset)
 {
 	unsigned int val = 0;

-	regmap_read(hdmi->regm, offset, &val);
+	regmap_read(hdmi->regm, offset << hdmi->reg_shift, &val);

 	return val;
 }

 static void hdmi_modb(struct dw_hdmi *hdmi, u8 data, u8 mask, unsigned reg)
 {
-	regmap_update_bits(hdmi->regm, reg, mask, data);
+	regmap_update_bits(hdmi->regm, reg << hdmi->reg_shift, mask, data);
 }

 static void hdmi_mask_writeb(struct dw_hdmi *hdmi, u8 data, unsigned int reg,
@@ -1984,11 +1985,10 @@ static const struct regmap_config hdmi_regmap_8bit_config = {
 };

 static const struct regmap_config hdmi_regmap_32bit_config = {
-	.reg_bits	= 8,
-	.pad_bits	= 24,
+	.reg_bits	= 32,
 	.val_bits	= 32,
 	.reg_stride	= 4,
-	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR,
+	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR << 2,
 };

 static struct dw_hdmi *
@@ -2044,6 +2044,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
 		switch (val) {
 		case 4:
 			reg_config = &hdmi_regmap_32bit_config;
+			hdmi->reg_shift = 2;
 			break;
 		case 1:
 			reg_config = &hdmi_regmap_8bit_config;

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