linux-kernel - Re: [PATCH v5 drm-dp 2/9] drm/hisilicon/hibmc: Add dp serdes cfg to adjust serdes rate, voltage and pre-emphasis

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Message-ID: <of75z5hy3pc5wvbd2rzmvpo2wdmap3iraj2vofldg6qeglvl2t@ogiq5nfeh4qe>
Date: Fri, 7 Mar 2025 12:51:13 +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 v5 drm-dp 2/9] drm/hisilicon/hibmc: Add dp serdes cfg to
 adjust serdes rate, voltage and pre-emphasis

On Fri, Mar 07, 2025 at 06:16:33PM +0800, Yongbang Shi wrote:
> From: Baihan Li <libaihan@...wei.com>
> 
> This dp controller need features of digital-to-analog conversion and
> high-speed transmission in chip by its extern serdes controller. Our
> serdes cfg is relatively simple, just need two register configurations.
> Don't need too much functions, like: power on/off, initialize, and some
> complex configurations, so I'm not going to use the phy framework.
> This serdes is inited and configured in dp initialization, and also
> integrating them into link training process.
> 
> For rate changing, we can change from 1.62-8.2Gpbs by cfg reg.
> For voltage and pre-emphasis levels changing, we can cfg different
> serdes ffe value.
> 
> Signed-off-by: Baihan Li <libaihan@...wei.com>
> Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
> ---
> ChangeLog:
> v3 -> v4:
>   - fix the serdes cfg in hibmc_dp_serdes_set_tx_cfg(), suggested by Dmitry Baryshkov.
>   - move the dp serdes registers to dp_reg.h, suggested by Dmitry Baryshkov.
>   - 
> v2 -> v3:
>   - add commit log about dp serdes, suggested by Dmitry Baryshkov.
>   - return value in hibmc_dp_serdes_init(), suggested by Dmitry Baryshkov.
>   - add static const in the array of serdes_tx_cfg[], suggested by Dmitry Baryshkov.
>   - change drm_warn to drm_dbg_dp, suggested by Dmitry Baryshkov.
>   - add explanations about dp serdes macros, suggested by Dmitry Baryshkov.
> v1 -> v2:
>   - splittting the patch and add more detailed the changes in the commit message, suggested by Dmitry Baryshkov.
>   - changing all names of dp phy to dp serdes.
> ---
>  drivers/gpu/drm/hisilicon/hibmc/Makefile      |  2 +-
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h  |  4 ++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    |  5 ++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h   | 23 ++++++
>  .../gpu/drm/hisilicon/hibmc/dp/dp_serdes.c    | 71 +++++++++++++++++++
>  5 files changed, 104 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/hisilicon/hibmc/dp/dp_serdes.c
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry