From mboxrd@z Thu Jan  1 00:00:00 1970
From: Adrian Ratiu <adrian.ratiu-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Subject: Re: [PATCH v5 1/5] drm: bridge: dw_mipi_dsi: add initial regmap
 infrastructure
Date: Tue, 31 Mar 2020 00:16:53 +0300
Message-ID: <87ftdp35mi.fsf@collabora.com>
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To: adrian61 <pop.adrian61-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jernej Skrabec <jernej.skrabec-gGgVlfcn5nU@public.gmane.org>, Jonas Karlman <jonas-uIzNG4q0ceqzQB+pC5nmwQ@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, Andrzej Hajda <a.hajda-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>, linux-imx-3arQi8VN3Tc@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, kernel-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org, linux-stm32-XDFAJ8BFU24N7RejjzZ/Li2xQDfSxrLKVpNB7YpNyf8@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Laurent Pinchart <Laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
List-Id: linux-rockchip.vger.kernel.org

On Mon, 30 Mar 2020, adrian61 <pop.adrian61-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hello Adrian, 
> 
> I am testing hese changes on my STM32F769-DISCO and i found 
> that: 
> 
> On Mon, Mar 30, 2020 at 2:35 PM Adrian Ratiu 
> <adrian.ratiu-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org> wrote: 
>> 
>> In order to support multiple versions of the Synopsis MIPI DSI 
>> host controller, which have different register layouts but 
>> almost identical HW protocols, we add a regmap infrastructure 
>> which can abstract away register accesses for platform drivers 
>> using the bridge. 
>> 
>> The controller HW revision is detected during bridge probe 
>> which will be used in future commits to load the relevant 
>> register layout which the bridge will use transparently to the 
>> platform drivers. 
>> 
>> Signed-off-by: Adrian Ratiu <adrian.ratiu-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org> --- 
>> New in v5.  --- 
>>  drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 208 
>>  ++++++++++-------- 1 file changed, 117 insertions(+), 91 
>>  deletions(-) 
>> 
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c 
>> b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c index 
>> 5ef0f154aa7b..6d9e2f21c9cc 100644 --- 
>> a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c +++ 
>> b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c @@ -15,6 +15,7 
>> @@ 
>>  #include <linux/module.h> #include <linux/of_device.h> 
>>  #include <linux/pm_runtime.h> 
>> +#include <linux/regmap.h> 
>>  #include <linux/reset.h> 
>> 
>>  #include <video/mipi_display.h> 
>> @@ -227,6 +228,7 @@ struct dw_mipi_dsi { 
>>         struct drm_bridge *panel_bridge; struct device *dev; 
>>         void __iomem *base; 
>> +       struct regmap *regs; 
>> 
>>         struct clk *pclk; 
>> 
>> @@ -235,6 +237,7 @@ struct dw_mipi_dsi { 
>>         u32 lanes; u32 format; unsigned long mode_flags; 
>> +       u32 hw_version; 
>> 
>>  #ifdef CONFIG_DEBUG_FS 
>>         struct dentry *debugfs; 
>> @@ -249,6 +252,13 @@ struct dw_mipi_dsi { 
>>         const struct dw_mipi_dsi_plat_data *plat_data; 
>>  }; 
>> 
>> +static const struct regmap_config dw_mipi_dsi_regmap_cfg = { + 
>> .reg_bits = 32, +       .val_bits = 32, +       .reg_stride = 
>> 4, +       .name = "dw-mipi-dsi", +}; + 
>>  /* 
>>   * Check if either a link to a master or slave is present */ 
>> @@ -280,16 +290,6 @@ static inline struct dw_mipi_dsi 
>> *bridge_to_dsi(struct drm_bridge *bridge) 
>>         return container_of(bridge, struct dw_mipi_dsi, 
>>         bridge); 
>>  } 
>> 
>> -static inline void dsi_write(struct dw_mipi_dsi *dsi, u32 reg, 
>> u32 val) -{ -       writel(val, dsi->base + reg); -} - -static 
>> inline u32 dsi_read(struct dw_mipi_dsi *dsi, u32 reg) -{ - 
>> return readl(dsi->base + reg); -} - 
>>  static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host, 
>>                                    struct mipi_dsi_device 
>>                                    *device) 
>>  { 
>> @@ -366,29 +366,29 @@ static void dw_mipi_message_config(struct 
>> dw_mipi_dsi *dsi, 
>>         if (lpm) 
>>                 val |= CMD_MODE_ALL_LP; 
>> 
>> -       dsi_write(dsi, DSI_LPCLK_CTRL, lpm ? 0 : 
>> PHY_TXREQUESTCLKHS); -       dsi_write(dsi, DSI_CMD_MODE_CFG, 
>> val); +       regmap_write(dsi->regs, DSI_LPCLK_CTRL, lpm ? 0 : 
>> PHY_TXREQUESTCLKHS); +       regmap_write(dsi->regs, 
>> DSI_CMD_MODE_CFG, val); 
>>  } 
>> 
>>  static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi 
>>  *dsi, u32 hdr_val) { 
>>         int ret; 
>> -       u32 val, mask; +       u32 val = 0, mask; 
>> 
>> -       ret = readl_poll_timeout(dsi->base + 
>> DSI_CMD_PKT_STATUS, -                                val, !(val 
>> & GEN_CMD_FULL), 1000, - 
>> CMD_PKT_STATUS_TIMEOUT_US); +       ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_CMD_PKT_STATUS, + 
>> val, !(val & GEN_CMD_FULL), 1000, + 
>> CMD_PKT_STATUS_TIMEOUT_US); 
>>         if (ret) { 
>>                 dev_err(dsi->dev, "failed to get available 
>>                 command FIFO\n"); return ret; 
>>         } 
>> 
>> -       dsi_write(dsi, DSI_GEN_HDR, hdr_val); + 
>> regmap_write(dsi->regs, DSI_GEN_HDR, hdr_val); 
>> 
>>         mask = GEN_CMD_EMPTY | GEN_PLD_W_EMPTY; 
>> -       ret = readl_poll_timeout(dsi->base + 
>> DSI_CMD_PKT_STATUS, -                                val, (val 
>> & mask) == mask, -                                1000, 
>> CMD_PKT_STATUS_TIMEOUT_US); +       ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_CMD_PKT_STATUS, + 
>> val, (val & mask) == mask, + 
>> 1000, CMD_PKT_STATUS_TIMEOUT_US); 
>>         if (ret) { 
>>                 dev_err(dsi->dev, "failed to write command 
>>                 FIFO\n"); return ret; 
>> @@ -403,24 +403,26 @@ static int dw_mipi_dsi_write(struct 
>> dw_mipi_dsi *dsi, 
>>         const u8 *tx_buf = packet->payload; int len = 
>>         packet->payload_length, pld_data_bytes = sizeof(u32), 
>>         ret; __le32 word; 
>> -       u32 val; +       u32 val = 0; 
>> 
>>         while (len) { 
>>                 if (len < pld_data_bytes) { 
>>                         word = 0; memcpy(&word, tx_buf, len); 
>> -                       dsi_write(dsi, DSI_GEN_PLD_DATA, 
>> le32_to_cpu(word)); + 
>> regmap_write(dsi->regs, DSI_GEN_PLD_DATA, + 
>> le32_to_cpu(word)); 
>>                         len = 0; 
>>                 } else { 
>>                         memcpy(&word, tx_buf, pld_data_bytes); 
>> -                       dsi_write(dsi, DSI_GEN_PLD_DATA, 
>> le32_to_cpu(word)); + 
>> regmap_write(dsi->regs, DSI_GEN_PLD_DATA, + 
>> le32_to_cpu(word)); 
>>                         tx_buf += pld_data_bytes; len -= 
>>                         pld_data_bytes; 
>>                 } 
>> 
>> -               ret = readl_poll_timeout(dsi->base + 
>> DSI_CMD_PKT_STATUS, - 
>> val, !(val & GEN_PLD_W_FULL), 1000, - 
>> CMD_PKT_STATUS_TIMEOUT_US); +               ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_CMD_PKT_STATUS, + 
>> val, !(val & GEN_PLD_W_FULL), + 
>> 1000, CMD_PKT_STATUS_TIMEOUT_US); 
>>                 if (ret) { 
>>                         dev_err(dsi->dev, 
>>                                 "failed to get available write 
>>                                 payload FIFO\n"); 
>> @@ -438,12 +440,12 @@ static int dw_mipi_dsi_read(struct 
>> dw_mipi_dsi *dsi, 
>>  { 
>>         int i, j, ret, len = msg->rx_len; u8 *buf = 
>>         msg->rx_buf; 
>> -       u32 val; +       u32 val = 0; 
>> 
>>         /* Wait end of the read operation */ 
>> -       ret = readl_poll_timeout(dsi->base + 
>> DSI_CMD_PKT_STATUS, -                                val, !(val 
>> & GEN_RD_CMD_BUSY), -                                1000, 
>> CMD_PKT_STATUS_TIMEOUT_US); +       ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_CMD_PKT_STATUS, + 
>> val, !(val & GEN_RD_CMD_BUSY), + 
>> 1000, CMD_PKT_STATUS_TIMEOUT_US); 
>>         if (ret) { 
>>                 dev_err(dsi->dev, "Timeout during read 
>>                 operation\n"); return ret; 
>> @@ -451,15 +453,15 @@ static int dw_mipi_dsi_read(struct 
>> dw_mipi_dsi *dsi, 
>> 
>>         for (i = 0; i < len; i += 4) { 
>>                 /* Read fifo must not be empty before all bytes 
>>                 are read */ 
>> -               ret = readl_poll_timeout(dsi->base + 
>> DSI_CMD_PKT_STATUS, - 
>> val, !(val & GEN_PLD_R_EMPTY), - 
>> 1000, CMD_PKT_STATUS_TIMEOUT_US); +               ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_CMD_PKT_STATUS, + 
>> val, !(val & GEN_PLD_R_EMPTY), + 
>> 1000, CMD_PKT_STATUS_TIMEOUT_US); 
>>                 if (ret) { 
>>                         dev_err(dsi->dev, "Read payload FIFO is 
>>                         empty\n"); return ret; 
>>                 } 
>> 
>> -               val = dsi_read(dsi, DSI_GEN_PLD_DATA); + 
>> regmap_read(dsi->regs, DSI_GEN_PLD_DATA, &val); 
>>                 for (j = 0; j < 4 && j + i < len; j++) 
>>                         buf[i + j] = val >> (8 * j); 
>>         } 
>> @@ -536,29 +538,29 @@ static void 
>> dw_mipi_dsi_video_mode_config(struct dw_mipi_dsi *dsi) 
>>         } 
>>  #endif /* CONFIG_DEBUG_FS */ 
>> 
>> -       dsi_write(dsi, DSI_VID_MODE_CFG, val); + 
>> regmap_write(dsi->regs, DSI_VID_MODE_CFG, val); 
>>  } 
>> 
>>  static void dw_mipi_dsi_set_mode(struct dw_mipi_dsi *dsi, 
>>                                  unsigned long mode_flags) 
>>  { 
>> -       dsi_write(dsi, DSI_PWR_UP, RESET); + 
>> regmap_write(dsi->regs, DSI_PWR_UP, RESET); 
>> 
>>         if (mode_flags & MIPI_DSI_MODE_VIDEO) { 
>> -               dsi_write(dsi, DSI_MODE_CFG, 
>> ENABLE_VIDEO_MODE); +               regmap_write(dsi->regs, 
>> DSI_MODE_CFG, ENABLE_VIDEO_MODE); 
>>                 dw_mipi_dsi_video_mode_config(dsi); 
>> -               dsi_write(dsi, DSI_LPCLK_CTRL, 
>> PHY_TXREQUESTCLKHS); +               regmap_write(dsi->regs, 
>> DSI_LPCLK_CTRL, PHY_TXREQUESTCLKHS); 
>>         } else { 
>> -               dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE); 
>> +               regmap_write(dsi->regs, DSI_MODE_CFG, 
>> ENABLE_CMD_MODE); 
>>         } 
>> 
>> -       dsi_write(dsi, DSI_PWR_UP, POWERUP); + 
>> regmap_write(dsi->regs, DSI_PWR_UP, POWERUP); 
>>  } 
>> 
>>  static void dw_mipi_dsi_disable(struct dw_mipi_dsi *dsi) { 
>> -       dsi_write(dsi, DSI_PWR_UP, RESET); - 
>> dsi_write(dsi, DSI_PHY_RSTZ, PHY_RSTZ); + 
>> regmap_write(dsi->regs, DSI_PWR_UP, RESET); + 
>> regmap_write(dsi->regs, DSI_PHY_RSTZ, PHY_RSTZ); 
>>  } 
>> 
>>  static void dw_mipi_dsi_init(struct dw_mipi_dsi *dsi) 
>> @@ -573,14 +575,14 @@ static void dw_mipi_dsi_init(struct 
>> dw_mipi_dsi *dsi) 
>>          */ 
>>         u32 esc_clk_division = (dsi->lane_mbps >> 3) / 20 + 1; 
>> 
>> -       dsi_write(dsi, DSI_PWR_UP, RESET); + 
>> regmap_write(dsi->regs, DSI_PWR_UP, RESET); 
>> 
>>         /* 
>>          * TODO dw drv improvements * timeout clock division 
>>          should be computed with the * high speed transmission 
>>          counter timeout and byte lane...  */ 
>> -       dsi_write(dsi, DSI_CLKMGR_CFG, TO_CLK_DIVISION(10) | + 
>> regmap_write(dsi->regs, DSI_CLKMGR_CFG, TO_CLK_DIVISION(10) | 
>>                   TX_ESC_CLK_DIVISION(esc_clk_division)); 
>>  } 
>> 
>> @@ -609,22 +611,22 @@ static void dw_mipi_dsi_dpi_config(struct 
>> dw_mipi_dsi *dsi, 
>>         if (mode->flags & DRM_MODE_FLAG_NHSYNC) 
>>                 val |= HSYNC_ACTIVE_LOW; 
>> 
>> -       dsi_write(dsi, DSI_DPI_VCID, DPI_VCID(dsi->channel)); - 
>> dsi_write(dsi, DSI_DPI_COLOR_CODING, color); - 
>> dsi_write(dsi, DSI_DPI_CFG_POL, val); + 
>> regmap_write(dsi->regs, DSI_DPI_VCID, DPI_VCID(dsi->channel)); 
>> +       regmap_write(dsi->regs, DSI_DPI_COLOR_CODING, color); + 
>> regmap_write(dsi->regs, DSI_DPI_CFG_POL, val); 
>>         /* 
>>          * TODO dw drv improvements * largest packet sizes 
>>          during hfp or during vsa/vpb/vfp * should be computed 
>>          according to byte lane, lane number and only * if 
>>          sending lp cmds in high speed is enable 
>>          (PHY_TXREQUESTCLKHS) */ 
>> -       dsi_write(dsi, DSI_DPI_LP_CMD_TIM, 
>> OUTVACT_LPCMD_TIME(4) +       regmap_write(dsi->regs, 
>> DSI_DPI_LP_CMD_TIM, OUTVACT_LPCMD_TIME(4) 
>>                   | INVACT_LPCMD_TIME(4)); 
>>  } 
>> 
>>  static void dw_mipi_dsi_packet_handler_config(struct 
>>  dw_mipi_dsi *dsi) { 
>> -       dsi_write(dsi, DSI_PCKHDL_CFG, CRC_RX_EN | ECC_RX_EN | 
>> BTA_EN); +       regmap_write(dsi->regs, DSI_PCKHDL_CFG, 
>> CRC_RX_EN | ECC_RX_EN | BTA_EN); 
>>  } 
>> 
>>  static void dw_mipi_dsi_video_packet_config(struct dw_mipi_dsi 
>>  *dsi, 
>> @@ -638,7 +640,7 @@ static void 
>> dw_mipi_dsi_video_packet_config(struct dw_mipi_dsi *dsi, 
>>          * non-burst video modes, see 
>>          dw_mipi_dsi_video_mode_config()...  */ 
>> 
>> -       dsi_write(dsi, DSI_VID_PKT_SIZE, + 
>> regmap_write(dsi->regs, DSI_VID_PKT_SIZE, 
>>                        dw_mipi_is_dual_mode(dsi) ? 
>>                                 VID_PKT_SIZE(mode->hdisplay / 
>>                                 2) : 
>>                                 VID_PKT_SIZE(mode->hdisplay)); 
>> @@ -651,14 +653,15 @@ static void 
>> dw_mipi_dsi_command_mode_config(struct dw_mipi_dsi *dsi) 
>>          * compute high speed transmission counter timeout 
>>          according * to the timeout clock division 
>>          (TO_CLK_DIVISION) and byte lane...  */ 
>> -       dsi_write(dsi, DSI_TO_CNT_CFG, HSTX_TO_CNT(1000) | 
>> LPRX_TO_CNT(1000)); +       regmap_write(dsi->regs, 
>> DSI_TO_CNT_CFG, +                    HSTX_TO_CNT(1000) | 
>> LPRX_TO_CNT(1000)); 
>>         /* 
>>          * TODO dw drv improvements * the Bus-Turn-Around 
>>          Timeout Counter should be computed * according to byte 
>>          lane...  */ 
>> -       dsi_write(dsi, DSI_BTA_TO_CNT, 0xd00); - 
>> dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE); + 
>> regmap_write(dsi->regs, DSI_BTA_TO_CNT, 0xd00); + 
>> regmap_write(dsi->regs, DSI_MODE_CFG, ENABLE_CMD_MODE); 
>>  } 
>> 
>>  /* Get lane byte clock cycles. */ 
>> @@ -692,13 +695,13 @@ static void 
>> dw_mipi_dsi_line_timer_config(struct dw_mipi_dsi *dsi, 
>>          * computations below may be improved...  */ 
>>         lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, 
>>         htotal); 
>> -       dsi_write(dsi, DSI_VID_HLINE_TIME, lbcc); + 
>> regmap_write(dsi->regs, DSI_VID_HLINE_TIME, lbcc); 
>> 
>>         lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, hsa); 
>> -       dsi_write(dsi, DSI_VID_HSA_TIME, lbcc); + 
>> regmap_write(dsi->regs, DSI_VID_HSA_TIME, lbcc); 
>> 
>>         lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, hbp); 
>> -       dsi_write(dsi, DSI_VID_HBP_TIME, lbcc); + 
>> regmap_write(dsi->regs, DSI_VID_HBP_TIME, lbcc); 
>>  } 
>> 
>>  static void dw_mipi_dsi_vertical_timing_config(struct 
>>  dw_mipi_dsi *dsi, 
>> @@ -711,10 +714,10 @@ static void 
>> dw_mipi_dsi_vertical_timing_config(struct dw_mipi_dsi *dsi, 
>>         vfp = mode->vsync_start - mode->vdisplay; vbp = 
>>         mode->vtotal - mode->vsync_end; 
>> 
>> -       dsi_write(dsi, DSI_VID_VACTIVE_LINES, vactive); - 
>> dsi_write(dsi, DSI_VID_VSA_LINES, vsa); -       dsi_write(dsi, 
>> DSI_VID_VFP_LINES, vfp); -       dsi_write(dsi, 
>> DSI_VID_VBP_LINES, vbp); +       regmap_write(dsi->regs, 
>> DSI_VID_VACTIVE_LINES, vactive); + 
>> regmap_write(dsi->regs, DSI_VID_VSA_LINES, vsa); + 
>> regmap_write(dsi->regs, DSI_VID_VFP_LINES, vfp); + 
>> regmap_write(dsi->regs, DSI_VID_VBP_LINES, vbp); 
>>  } 
>> 
>>  static void dw_mipi_dsi_dphy_timing_config(struct dw_mipi_dsi 
>>  *dsi) 
>> @@ -737,23 +740,25 @@ static void 
>> dw_mipi_dsi_dphy_timing_config(struct dw_mipi_dsi *dsi) 
>>          * DSI_CMD_MODE_CFG.MAX_RD_PKT_SIZE_LP (see 
>>          CMD_MODE_ALL_LP) */ 
>> 
>> -       hw_version = dsi_read(dsi, DSI_VERSION) & VERSION; + 
>> regmap_read(dsi->regs, DSI_VERSION, &hw_version); + 
>> hw_version &= VERSION; 
>> 
>>         if (hw_version >= HWVER_131) { 
>> -               dsi_write(dsi, DSI_PHY_TMR_CFG, - 
>> PHY_HS2LP_TIME_V131(timing.data_hs2lp) | - 
>> PHY_LP2HS_TIME_V131(timing.data_lp2hs)); - 
>> dsi_write(dsi, DSI_PHY_TMR_RD_CFG, MAX_RD_TIME_V131(10000)); + 
>> regmap_write(dsi->regs, DSI_PHY_TMR_CFG, + 
>> PHY_HS2LP_TIME_V131(timing.data_hs2lp) | + 
>> PHY_LP2HS_TIME_V131(timing.data_lp2hs)); + 
>> regmap_write(dsi->regs, DSI_PHY_TMR_RD_CFG, + 
>> MAX_RD_TIME_V131(10000)); 
>>         } else { 
>> -               dsi_write(dsi, DSI_PHY_TMR_CFG, - 
>> PHY_HS2LP_TIME(timing.data_hs2lp) | - 
>> PHY_LP2HS_TIME(timing.data_lp2hs) | - 
>> MAX_RD_TIME(10000)); +               regmap_write(dsi->regs, 
>> DSI_PHY_TMR_CFG, + 
>> PHY_HS2LP_TIME(timing.data_hs2lp) | + 
>> PHY_LP2HS_TIME(timing.data_lp2hs) | + 
>> MAX_RD_TIME(10000)); 
>>         } 
>> 
>> -       dsi_write(dsi, DSI_PHY_TMR_LPCLK_CFG, - 
>> PHY_CLKHS2LP_TIME(timing.clk_hs2lp) | - 
>> PHY_CLKLP2HS_TIME(timing.clk_lp2hs)); + 
>> regmap_write(dsi->regs, DSI_PHY_TMR_LPCLK_CFG, + 
>> PHY_CLKHS2LP_TIME(timing.clk_hs2lp) | + 
>> PHY_CLKLP2HS_TIME(timing.clk_lp2hs)); 
>>  } 
>> 
>>  static void dw_mipi_dsi_dphy_interface_config(struct 
>>  dw_mipi_dsi *dsi) 
>> @@ -763,46 +768,49 @@ static void 
>> dw_mipi_dsi_dphy_interface_config(struct dw_mipi_dsi *dsi) 
>>          * stop wait time should be the maximum between host 
>>          dsi * and panel stop wait times */ 
>> -       dsi_write(dsi, DSI_PHY_IF_CFG, PHY_STOP_WAIT_TIME(0x20) 
>> | -                 N_LANES(dsi->lanes)); + 
>> regmap_write(dsi->regs, DSI_PHY_IF_CFG, + 
>> PHY_STOP_WAIT_TIME(0x20) | N_LANES(dsi->lanes)); 
>>  } 
>> 
>>  static void dw_mipi_dsi_dphy_init(struct dw_mipi_dsi *dsi) { 
>>         /* Clear PHY state */ 
>> -       dsi_write(dsi, DSI_PHY_RSTZ, PHY_DISFORCEPLL | 
>> PHY_DISABLECLK -                 | PHY_RSTZ | PHY_SHUTDOWNZ); - 
>> dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLR); - 
>> dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_TESTCLR); - 
>> dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLR); + 
>> regmap_write(dsi->regs, DSI_PHY_RSTZ, PHY_DISFORCEPLL | 
>> PHY_DISABLECLK +                    | PHY_RSTZ | 
>> PHY_SHUTDOWNZ); +       regmap_write(dsi->regs, 
>> DSI_PHY_TST_CTRL0, PHY_UNTESTCLR); + 
>> regmap_write(dsi->regs, DSI_PHY_TST_CTRL0, PHY_TESTCLR); + 
>> regmap_write(dsi->regs, DSI_PHY_TST_CTRL0, PHY_UNTESTCLR); 
>>  } 
>> 
>>  static void dw_mipi_dsi_dphy_enable(struct dw_mipi_dsi *dsi) { 
>> -       u32 val; +       u32 val = 0; 
>>         int ret; 
>> 
>> -       dsi_write(dsi, DSI_PHY_RSTZ, PHY_ENFORCEPLL | 
>> PHY_ENABLECLK | -                 PHY_UNRSTZ | 
>> PHY_UNSHUTDOWNZ); +       regmap_write(dsi->regs, DSI_PHY_RSTZ, 
>> PHY_ENFORCEPLL | PHY_ENABLECLK | + 
>> PHY_UNRSTZ | PHY_UNSHUTDOWNZ); 
>> 
>> -       ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS, 
>> val, -                                val & PHY_LOCK, 1000, 
>> PHY_STATUS_TIMEOUT_US); +       ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_PHY_STATUS, + 
>> val, val & PHY_LOCK, + 
>> 1000, PHY_STATUS_TIMEOUT_US); 
>>         if (ret) 
>>                 DRM_DEBUG_DRIVER("failed to wait phy lock 
>>                 state\n"); 
>> 
>> -       ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS, - 
>> val, val & PHY_STOP_STATE_CLK_LANE, 1000, - 
>> PHY_STATUS_TIMEOUT_US); +       ret = 
>> regmap_read_poll_timeout(dsi->regs, DSI_PHY_STATUS, + 
>> val, val & PHY_STOP_STATE_CLK_LANE, 1000, + 
>> PHY_STATUS_TIMEOUT_US); 
>>         if (ret) 
>>                 DRM_DEBUG_DRIVER("failed to wait phy clk lane 
>>                 stop state\n"); 
>>  } 
>> 
>>  static void dw_mipi_dsi_clear_err(struct dw_mipi_dsi *dsi) { 
>> -       dsi_read(dsi, DSI_INT_ST0); -       dsi_read(dsi, 
>> DSI_INT_ST1); -       dsi_write(dsi, DSI_INT_MSK0, 0); - 
>> dsi_write(dsi, DSI_INT_MSK1, 0); +       u32 val; + + 
>> regmap_read(dsi->regs, DSI_INT_ST0, &val); + 
>> regmap_read(dsi->regs, DSI_INT_ST1, &val); + 
>> regmap_write(dsi->regs, DSI_INT_MSK0, 0); + 
>> regmap_write(dsi->regs, DSI_INT_MSK1, 0); 
>>  } 
>> 
>>  static void dw_mipi_dsi_bridge_post_disable(struct drm_bridge 
>>  *bridge) 
>> @@ -989,6 +997,14 @@ static void 
>> dw_mipi_dsi_debugfs_remove(struct dw_mipi_dsi *dsi) { } 
>> 
>>  #endif /* CONFIG_DEBUG_FS */ 
>> 
>> +static void dw_mipi_dsi_get_hw_version(struct dw_mipi_dsi 
>> *dsi) +{ +       regmap_read(dsi->regs, DSI_VERSION, 
>> &dsi->hw_version); +       dsi->hw_version &= VERSION; + 
>> if (!dsi->hw_version) 
> Here, this is 0 on my board. 

So we did a live debugging session on the STM board and managed to 
root cause this. The regmap series uncovered a bug introduced by 
the upstream commit fa6251a747b7 ("drm/stm: dsi: check hardware 
version") which disables the peripheral clock immediately after 
reading the version, but it appears that clock is still required 
for the other reads to succeed, otherwise 0 values are read and 
register writes have no effect (display
remains black).

This obviously only happens on the stm driver, will post a fix in 
v6.

Thanks Adrian, much appreciated!

>> +               dev_err(dsi->dev, "Failed to read DSI hw version register\n");
>> +}
>> +
>>  static struct dw_mipi_dsi *
>>  __dw_mipi_dsi_probe(struct platform_device *pdev,
>>                     const struct dw_mipi_dsi_plat_data *plat_data)
>> @@ -1020,6 +1036,14 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>                 dsi->base = plat_data->base;
>>         }
>>
>> +       dsi->regs = devm_regmap_init_mmio(dev, dsi->base,
>> +                                         &dw_mipi_dsi_regmap_cfg);
>> +       if (IS_ERR(dsi->regs)) {
>> +               ret = PTR_ERR(dsi->regs);
>> +               DRM_ERROR("Failed to create DW MIPI DSI regmap: %d\n", ret);
>> +               return ERR_PTR(ret);
>> +       }
>> +
>>         dsi->pclk = devm_clk_get(dev, "pclk");
>>         if (IS_ERR(dsi->pclk)) {
>>                 ret = PTR_ERR(dsi->pclk);
>> @@ -1055,6 +1079,8 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>                 clk_disable_unprepare(dsi->pclk);
>>         }
>>
>> +       dw_mipi_dsi_get_hw_version(dsi);
>> +
>>         dw_mipi_dsi_debugfs_init(dsi);
>>         pm_runtime_enable(dev);
>>
>> --
>> 2.26.0
>>
>>
>> _______________________________________________
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>> linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> Best regards,
> Adrian
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip