linux-kernel - Re: [PATCH v6 drm-dp 2/5] drm/hisilicon/hibmc: add dp link moduel in hibmc

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Message-ID: <yyunb5oxzlmrrcxlsrub4j7iwwpaptbvubbtxr3omjftietc5b@3tfg2ldxeaoa>
Date: Fri, 6 Dec 2024 01:25:47 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Yongbang Shi <shiyongbang@...wei.com>
Cc: xinliang.liu@...aro.org, tiantao6@...ilicon.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, 
	daniel@...ll.ch, kong.kongxinwei@...ilicon.com, liangjian010@...wei.com, 
	chenjianmin@...wei.com, lidongming5@...wei.com, libaihan@...wei.com, 
	shenjian15@...wei.com, shaojijie@...wei.com, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 drm-dp 2/5] drm/hisilicon/hibmc: add dp link moduel in
 hibmc

On Mon, Dec 02, 2024 at 09:13:19PM +0800, Yongbang Shi wrote:
> From: baihan li <libaihan@...wei.com>
> 
> Add link training process functions in this moduel.
> 
> Signed-off-by: Baihan Li <libaihan@...wei.com>
> Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
> ---
> Changelog:
> v5 -> v6:
>   - using drm_dbg_dp() to print debug info instead of drm_info(), suggested by Dmitry Baryshkov.
> v3 -> v4:
>   - optimizing hibmc_dp_link_get_adjust_train() to delete for loop, suggested by Dmitry Baryshkov.
>   - changing ELNRNG to EIO error code, suggested by Dmitry Baryshkov.
>   - deleting meaningless macro, suggested by Dmitry Baryshkov.
>   - fixing build errors reported by kernel test robot <lkp@...el.com>
>     Closes: https://lore.kernel.org/oe-kbuild-all/202411041559.WIfxRN6n-lkp@intel.com/
> v2 -> v3:
>   - using switchcase in dp_link_reduce_lane, suggested by Dmitry Baryshkov.
>   - deleting dp_link_pattern2dpcd function and using macros directly, suggested by Dmitry Baryshkov.
>   - deleting EFAULT error codes, suggested by Dmitry Baryshkov.
> v1 -> v2:
>   - using drm_dp_* functions implement dp link training process, suggested by Jani Nikula.
>   - fix build errors reported by kernel test robot <lkp@...el.com>
>     Closes: https://lore.kernel.org/oe-kbuild-all/202410031735.8iRZZR6T-lkp@intel.com/
>   v1:https://lore.kernel.org/all/20240930100610.782363-1-shiyongbang@huawei.com/
> ---
>  drivers/gpu/drm/hisilicon/hibmc/Makefile     |   2 +-
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h |  24 ++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c | 339 +++++++++++++++++++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h  |   8 +
>  4 files changed, 372 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
> 
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/Makefile b/drivers/gpu/drm/hisilicon/hibmc/Makefile
> index 8770ec6dfffd..94d77da88bbf 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/Makefile
> +++ b/drivers/gpu/drm/hisilicon/hibmc/Makefile
> @@ -1,5 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_de.o hibmc_drm_vdac.o hibmc_drm_i2c.o \
> -	       dp/dp_aux.o
> +	       dp/dp_aux.o dp/dp_link.o
>  
>  obj-$(CONFIG_DRM_HISI_HIBMC) += hibmc-drm.o
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
> index 7d3cd32393c0..8422999acbf0 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
> @@ -13,11 +13,34 @@
>  #include <linux/io.h>
>  #include <drm/display/drm_dp_helper.h>
>  
> +#define HIBMC_DP_LANE_NUM_MAX 2
> +
> +struct hibmc_link_status {
> +	bool clock_recovered;
> +	bool channel_equalized;
> +};
> +
> +struct hibmc_link_cap {
> +	int rx_dpcd_revision;
> +	u8 link_rate;
> +	u8 lanes;
> +	bool is_tps3;
> +	bool is_tps4;

These two fields are set neither in this patch nor in any of the
following patches.

> +};
> +

[...]

> +static int hibmc_dp_link_training_configure(struct hibmc_dp_dev *dp)
> +{
> +	u8 buf[2];
> +	int ret;
> +
> +	/* DP 2 lane */
> +	hibmc_dp_reg_write_field(dp, HIBMC_DP_PHYIF_CTRL0, HIBMC_DP_CFG_LANE_DATA_EN,
> +				 dp->link.cap.lanes == 0x2 ? 0x3 : 0x1);
> +	hibmc_dp_reg_write_field(dp, HIBMC_DP_DPTX_GCTL0, HIBMC_DP_CFG_PHY_LANE_NUM,
> +				 dp->link.cap.lanes == 0x2 ? 0x1 : 0);
> +
> +	/* enhanced frame */
> +	hibmc_dp_reg_write_field(dp, HIBMC_DP_VIDEO_CTRL, HIBMC_DP_CFG_STREAM_FRAME_MODE, 0x1);
> +
> +	/* set rate and lane count */
> +	buf[0] = dp->link.cap.link_rate;
> +	buf[1] = DP_LANE_COUNT_ENHANCED_FRAME_EN | dp->link.cap.lanes;
> +	ret = drm_dp_dpcd_write(&dp->aux, DP_LINK_BW_SET, buf, sizeof(buf));
> +	if (ret != sizeof(buf)) {
> +		drm_dbg_dp(dp->dev, "dp aux write link rate and lanes failed, ret: %d\n", ret);
> +		return ret >= 0 ? -EIO : ret;
> +	}
> +
> +	/* set 8b/10b and downspread */
> +	buf[0] = 0x10;

DP_SPREAD_AMP_0_5

> +	buf[1] = 0x1;

DP_SET_ANSI_8B10B

> +	ret = drm_dp_dpcd_write(&dp->aux, DP_DOWNSPREAD_CTRL, buf, sizeof(buf));
> +	if (ret != sizeof(buf)) {
> +		drm_dbg_dp(dp->dev, "dp aux write 8b/10b and downspread failed, ret: %d\n", ret);
> +		return ret >= 0 ? -EIO : ret;
> +	}
> +
> +	ret = drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd);
> +	if (ret)
> +		drm_err(dp->dev, "dp aux read dpcd failed, ret: %d\n", ret);
> +
> +	return ret;
> +}
> +

-- 
With best wishes
Dmitry