Message-ID: <9e38774d-0028-6988-1be1-2e726c5ed4ab@collabora.com>
Date:   Wed, 18 Dec 2019 16:21:54 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Ezequiel Garcia <ezequiel@...labora.com>,
        linux-kernel@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>
Cc:     Collabora Kernel ML <kernel@...labora.com>, matthias.bgg@...il.com,
        drinkcat@...omium.org, hsinyi@...omium.org,
        Jitao Shi <jitao.shi@...iatek.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Ulrich Hecht <uli@...nd.eu>,
        linux-arm-kernel@...ts.infradead.org,
        Andrzej Hajda <a.hajda@...sung.com>,
        Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-mediatek@...ts.infradead.org,
        David Airlie <airlied@...ux.ie>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH v21 2/2] drm/bridge: Add I2C based driver for ps8640
 bridge

Hi Ezequiel,

Many thanks for the review, I am just preparing the next version to send.

On 16/12/19 18:07, Ezequiel Garcia wrote:
> On Mon, 2019-12-16 at 14:58 +0100, Enric Balletbo i Serra wrote:
>> From: Jitao Shi <jitao.shi@...iatek.com>
>>
>> This patch adds drm_bridge driver for parade DSI to eDP bridge chip.
>>
>> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
>> Reviewed-by: Daniel Kurtz <djkurtz@...omium.org>
>> Reviewed-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>> [uli: followed API changes, removed FW update feature]
>> Signed-off-by: Ulrich Hecht <uli@...nd.eu>
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>> ---
>>
>> Changes in v21:
>>  - Use devm_i2c_new_dummy_device and fix build issue using deprecated i2c_new_dummy
>>  - Fix build issue due missing drm_bridge.h
>>  - Do not remove in ps8640_remove device managed resources
>>
>> Changes in v19:
>>  - fixed return value of ps8640_probe() when no panel is found
>>
>> Changes in v18:
>>  - followed DRM API changes
>>  - use DEVICE_ATTR_RO()
>>  - remove firmware update code
>>  - add SPDX identifier
>>
>> Changes in v17:
>>  - remove some unused head files.
>>  - add macros for ps8640 pages.
>>  - remove ddc_i2c client
>>  - add mipi_dsi_device_register_full
>>  - remove the manufacturer from the name and i2c_device_id
>>
>> Changes in v16:
>>  - Disable ps8640 DSI MCS Function.
>>  - Rename gpios name more clearly.
>>  - Tune the ps8640 power on sequence.
>>
>> Changes in v15:
>>  - Drop drm_connector_(un)register calls from parade ps8640.
>>    The main DRM driver mtk_drm_drv now calls
>>    drm_connector_register_all() after drm_dev_register() in the
>>    mtk_drm_bind() function. That function should iterate over all
>>    connectors and call drm_connector_register() for each of them.
>>    So, remove drm_connector_(un)register calls from parade ps8640.
>>
>> Changes in v14:
>>  - update copyright info.
>>  - change bridge_to_ps8640 and connector_to_ps8640 to inline function.
>>  - fix some coding style.
>>  - use sizeof as array counter.
>>  - use drm_get_edid when read edid.
>>  - add mutex when firmware updating.
>>
>> Changes in v13:
>>  - add const on data, ps8640_write_bytes(struct i2c_client *client, const u8 *data, u16 data_len)
>>  - fix PAGE2_SW_REST tyro.
>>  - move the buf[3] init to entrance of the function.
>>
>> Changes in v12:
>>  - fix hw_chip_id build warning
>>
>> Changes in v11:
>>  - Remove depends on I2C, add DRM depends
>>  - Reuse ps8640_write_bytes() in ps8640_write_byte()
>>  - Use timer check for polling like the routines in <linux/iopoll.h>
>>  - Fix no drm_connector_unregister/drm_connector_cleanup when ps8640_bridge_attach fail
>>  - Check the ps8640 hardware id in ps8640_validate_firmware
>>  - Remove fw_version check
>>  - Move ps8640_validate_firmware before ps8640_enter_bl
>>  - Add ddc_i2c unregister when probe fail and ps8640_remove
>>
>>  drivers/gpu/drm/bridge/Kconfig         |  11 +
>>  drivers/gpu/drm/bridge/Makefile        |   1 +
>>  drivers/gpu/drm/bridge/parade-ps8640.c | 655 +++++++++++++++++++++++++
>>  3 files changed, 667 insertions(+)
>>  create mode 100644 drivers/gpu/drm/bridge/parade-ps8640.c
>>
>> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
>> index 4734f6993858..3e0a63011723 100644
>> --- a/drivers/gpu/drm/bridge/Kconfig
>> +++ b/drivers/gpu/drm/bridge/Kconfig
>> @@ -101,6 +101,17 @@ config DRM_PARADE_PS8622
>>  	---help---
>>  	  Parade eDP-LVDS bridge chip driver.
>>  
>> +config DRM_PARADE_PS8640
>> +	tristate "Parade PS8640 MIPI DSI to eDP Converter"
>> +	depends on OF
>> +	select DRM_KMS_HELPER
>> +	select DRM_MIPI_DSI
>> +	select DRM_PANEL
>> +	help
>> +	  Choose this option if you have PS8640 for display
>> +	  The PS8640 is a high-performance and low-power
>> +	  MIPI DSI to eDP converter
>> +
>>  config DRM_SIL_SII8620
>>  	tristate "Silicon Image SII8620 HDMI/MHL bridge"
>>  	depends on OF
>> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
>> index 1c0c92667ac4..91490c595b38 100644
>> --- a/drivers/gpu/drm/bridge/Makefile
>> +++ b/drivers/gpu/drm/bridge/Makefile
>> @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o
>>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
>>  obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
>> +obj-$(CONFIG_DRM_PARADE_PS8640) += parade-ps8640.o
>>  obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
>>  obj-$(CONFIG_DRM_SII902X) += sii902x.o
>>  obj-$(CONFIG_DRM_SII9234) += sii9234.o
>> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
>> new file mode 100644
>> index 000000000000..ab896ceb1a42
>> --- /dev/null
>> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
>> @@ -0,0 +1,655 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2016 MediaTek Inc.
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +//#include <linux/firmware.h>
> 
> Commented stuff should gone.
> 

Ack

>> +#include <linux/gpio/consumer.h>
>> +#include <linux/i2c.h>
>> +#include <linux/module.h>
>> +#include <linux/of_graph.h>
>> +#include <linux/regulator/consumer.h>
>> +//#include <asm/unaligned.h>
> 
> Ditto.
> 

Ack

>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_bridge.h>
>> +#include <drm/drm_crtc_helper.h>
>> +#include <drm/drm_edid.h>
>> +#include <drm/drm_mipi_dsi.h>
>> +#include <drm/drm_panel.h>
>> +#include <drm/drm_print.h>
>> +#include <drm/drm_probe_helper.h>
>> +
>> +#define PAGE1_VSTART		0x6b
>> +#define PAGE2_SPI_CFG3		0x82
>> +#define I2C_TO_SPI_RESET	0x20
>> +#define PAGE2_ROMADD_BYTE1	0x8e
>> +#define PAGE2_ROMADD_BYTE2	0x8f
>> +#define PAGE2_SWSPI_WDATA	0x90
>> +#define PAGE2_SWSPI_RDATA	0x91
>> +#define PAGE2_SWSPI_LEN		0x92
>> +#define PAGE2_SWSPI_CTL		0x93
>> +#define TRIGGER_NO_READBACK	0x05
>> +#define TRIGGER_READBACK	0x01
>> +#define PAGE2_SPI_STATUS	0x9e
>> +#define SPI_READY		0x0c
>> +#define PAGE2_GPIO_L		0xa6
>> +#define PAGE2_GPIO_H		0xa7
>> +#define PS_GPIO9		BIT(1)
>> +#define PAGE2_IROM_CTRL		0xb0
>> +#define IROM_ENABLE		0xc0
>> +#define IROM_DISABLE		0x80
>> +#define PAGE2_SW_RESET		0xbc
>> +#define SPI_SW_RESET		BIT(7)
>> +#define MPU_SW_RESET		BIT(6)
>> +#define PAGE2_ENCTLSPI_WR	0xda
>> +#define PAGE2_I2C_BYPASS	0xea
>> +#define I2C_BYPASS_EN		0xd0
>> +#define PAGE2_MCS_EN		0xf3
>> +#define MCS_EN			BIT(0)
>> +#define PAGE3_SET_ADD		0xfe
>> +#define PAGE3_SET_VAL		0xff
>> +#define VDO_CTL_ADD		0x13
>> +#define VDO_DIS			0x18
>> +#define VDO_EN			0x1c
>> +#define PAGE4_REV_L		0xf0
>> +#define PAGE4_REV_H		0xf1
>> +#define PAGE4_CHIP_L		0xf2
>> +#define PAGE4_CHIP_H		0xf3
>> +
>> +#define PAGE0_DP_CNTL		0
> 
> Unused macro.
> 
>> +#define PAGE1_VDO_BDG		1
>> +#define PAGE2_TOP_CNTL		2
>> +#define PAGE3_DSI_CNTL1		3
>> +#define PAGE4_MIPI_PHY		4
> 
> Ditto... maybe others as well?
> 

I removed all the unused macros.

>> +#define PAGE5_VPLL		5
>> +#define PAGE6_DSI_CNTL2		6
>> +#define PAGE7_SPI_CNTL		7
>> +#define MAX_DEVS		0x8
>> +
>> +struct ps8640_info {
>> +	u8 family_id;
>> +	u8 variant_id;
>> +	u16 version;
>> +};
>> +
>> +struct ps8640 {
>> +	struct drm_connector connector;
>> +	struct drm_bridge bridge;
>> +	struct edid *edid;
>> +	struct mipi_dsi_device *dsi;
>> +	struct i2c_client *page[MAX_DEVS];
>> +	struct regulator_bulk_data supplies[2];
>> +	struct drm_panel *panel;
>> +	struct gpio_desc *gpio_reset;
>> +	struct gpio_desc *gpio_power_down;
>> +	struct gpio_desc *gpio_mode_sel;
>> +	bool enabled;
>> +
>> +	/* firmware file info */
>> +	struct ps8640_info info;
>> +	bool in_fw_update;
>> +	/* for firmware update protect */
>> +	struct mutex fw_mutex;
>> +};
>> +
>> +static const u8 enc_ctrl_code[6] = { 0xaa, 0x55, 0x50, 0x41, 0x52, 0x44 };
>> +static const u8 hw_chip_id[4] = { 0x00, 0x0a, 0x00, 0x30 };
>> +
> 
> More unused stuff. Left-overs?
> 

Ack

>> +static inline struct ps8640 *bridge_to_ps8640(struct drm_bridge *e)
>> +{
>> +	return container_of(e, struct ps8640, bridge);
>> +}
>> +
>> +static inline struct ps8640 *connector_to_ps8640(struct drm_connector *e)
>> +{
>> +	return container_of(e, struct ps8640, connector);
>> +}
>> +
>> +static int ps8640_read(struct i2c_client *client, u8 reg, u8 *data,
>> +		       u16 data_len)
>> +{
>> +	int ret;
>> +	struct i2c_msg msgs[] = {
>> +		{
>> +		 .addr = client->addr,
>> +		 .flags = 0,
>> +		 .len = 1,
>> +		 .buf = &reg,
>> +		},
>> +		{
>> +		 .addr = client->addr,
>> +		 .flags = I2C_M_RD,
>> +		 .len = data_len,
>> +		 .buf = data,
>> +		}
>> +	};
>> +
>> +	ret = i2c_transfer(client->adapter, msgs, 2);
>> +
>> +	if (ret == 2)
>> +		return 0;
>> +	if (ret < 0)
>> +		return ret;
>> +	else
>> +		return -EIO;
>> +}
>> +
>> +static int ps8640_write_bytes(struct i2c_client *client, const u8 *data,
>> +			      u16 data_len)
>> +{
>> +	int ret;
>> +	struct i2c_msg msg;
>> +
>> +	msg.addr = client->addr;
>> +	msg.flags = 0;
>> +	msg.len = data_len;
>> +	msg.buf = (u8 *)data;
>> +
>> +	ret = i2c_transfer(client->adapter, &msg, 1);
>> +	if (ret == 1)
>> +		return 0;
>> +	if (ret < 0)
>> +		return ret;
>> +	else
>> +		return -EIO;
>> +}
>> +
>> +static int ps8640_write_byte(struct i2c_client *client, u8 reg, u8 data)
>> +{
>> +	u8 buf[] = { reg, data };
>> +
> 
> I was gonna say you should avoid transmitting data
> in the stack, but then I noticed the I2C core doesn't
> complaint about it (doesn't use object_is_on_stack).
> 
> Wolfram, does the I2C accept stacked (possibly non-DMA-able) objects?
> 
>> +	return ps8640_write_bytes(client, buf, sizeof(buf));
>> +}
>> +
>> +static void ps8640_get_mcu_fw_version(struct ps8640 *ps_bridge)
>> +{
>> +	struct i2c_client *client = ps_bridge->page[PAGE5_VPLL];
>> +	u8 fw_ver[2];
>> +
>> +	ps8640_read(client, 0x4, fw_ver, sizeof(fw_ver));
>> +	ps_bridge->info.version = (fw_ver[0] << 8) | fw_ver[1];
>> +
>> +	DRM_INFO_ONCE("ps8640 rom fw version %d.%d\n", fw_ver[0], fw_ver[1]);
> 
> Hm, isn't this too verbose?
> 

I think I can just remove this print as this info will be available in sysfs

>> +}
>> +
>> +static int ps8640_bridge_unmute(struct ps8640 *ps_bridge)
>> +{
>> +	struct i2c_client *client = ps_bridge->page[PAGE3_DSI_CNTL1];
>> +	u8 vdo_ctrl_buf[3] = { PAGE3_SET_ADD, VDO_CTL_ADD, VDO_EN };
>> +
>> +	return ps8640_write_bytes(client, vdo_ctrl_buf, sizeof(vdo_ctrl_buf));
>> +}
>> +
>> +static int ps8640_bridge_mute(struct ps8640 *ps_bridge)
>> +{
>> +	struct i2c_client *client = ps_bridge->page[PAGE3_DSI_CNTL1];
>> +	u8 vdo_ctrl_buf[3] = { PAGE3_SET_ADD, VDO_CTL_ADD, VDO_DIS };
>> +
>> +	return ps8640_write_bytes(client, vdo_ctrl_buf, sizeof(vdo_ctrl_buf));
>> +}
>> +
>> +static void ps8640_pre_enable(struct drm_bridge *bridge)
>> +{
>> +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
>> +	struct i2c_client *client = ps_bridge->page[PAGE2_TOP_CNTL];
>> +	struct i2c_client *page1 = ps_bridge->page[PAGE1_VDO_BDG];
>> +	int err;
>> +	u8 set_vdo_done, mcs_en, vstart;
>> +	ktime_t timeout;
>> +
>> +	if (ps_bridge->in_fw_update)
>> +		return;
>> +
>> +	if (ps_bridge->enabled)
>> +		return;
>> +
>> +	err = drm_panel_prepare(ps_bridge->panel);
>> +	if (err < 0) {
>> +		DRM_ERROR("failed to prepare panel: %d\n", err);
>> +		return;
>> +	}
>> +
>> +	err = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies),
>> +				    ps_bridge->supplies);
>> +	if (err < 0) {
>> +		DRM_ERROR("cannot enable regulators %d\n", err);
>> +		goto err_panel_unprepare;
>> +	}
>> +
>> +	gpiod_set_value(ps_bridge->gpio_power_down, 1);
>> +	gpiod_set_value(ps_bridge->gpio_reset, 0);
>> +	usleep_range(2000, 2500);
>> +	gpiod_set_value(ps_bridge->gpio_reset, 1);
>> +
>> +	/*
>> +	 * Wait for the ps8640 embed mcu ready
>> +	 * First wait 200ms and then check the mcu ready flag every 20ms
>> +	 */
>> +	msleep(200);
>> +
>> +	timeout = ktime_add_ms(ktime_get(), 200);
>> +	for (;;) {
>> +		err = ps8640_read(client, PAGE2_GPIO_H, &set_vdo_done, 1);
>> +		if (err < 0) {
>> +			DRM_ERROR("failed read PAGE2_GPIO_H: %d\n", err);
>> +			goto err_regulators_disable;
>> +		}
>> +		if ((set_vdo_done & PS_GPIO9) == PS_GPIO9)
>> +			break;
>> +		if (ktime_compare(ktime_get(), timeout) > 0)
>> +			break;
>> +		msleep(20);
>> +	}
> 
> I believe it's cleaner to use this idiom:
> 
>         unsigned long timeout = jiffies + msecs_to_jiffies(YOUR_DRIVER_TIMEOUT);
>         
>         while (time_is_after_jiffies(timeout)) {
>                 ....
>         }
> 

Agree, is more readable, so I changed it.

>> +
>> +	msleep(50);
>> +
>> +	ps8640_read(page1, PAGE1_VSTART, &vstart, 1);
>> +	DRM_INFO("PS8640 PAGE1.0x6B = 0x%x\n", vstart);
>> +
> 
> Ditto, isn't this too verbose?
> 

Ack, also is not really needed so I just removed it.

> I stopped reviewing at this point. It sounds like this driver
> could use some love. (Not sure how this driver stood twenty reviews :-))
> 
> Thanks,
> Ezequiel
> 

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