linux-kernel - Re: [PATCH 2/4] media: aspeed: Use FIELD

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Message-ID: <CACPK8XcmcP=vu8pWVKdiQVokPyh39Tuy0mfmgPSzb0wb0tcJuA@mail.gmail.com>
Date:   Wed, 22 Dec 2021 00:59:58 +0000
From:   Joel Stanley <joel@....id.au>
To:     Jammy Huang <jammy_huang@...eedtech.com>
Cc:     Eddie James <eajames@...ux.ibm.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Andrew Jeffery <andrew@...id.au>, linux-media@...r.kernel.org,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-aspeed <linux-aspeed@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] media: aspeed: Use FIELD_GET to improve readability

On Fri, 17 Dec 2021 at 09:53, Jammy Huang <jammy_huang@...eedtech.com> wrote:
>
> Use the bitfield macro FIELD_GET, and GENMASK to do the shift and mask in
> one go for reg values.
>
> Signed-off-by: Jammy Huang <jammy_huang@...eedtech.com>
> ---
>  drivers/media/platform/aspeed-video.c | 35 ++++++++++++---------------
>  1 file changed, 16 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
> index d5f77b205175..581a4261f9b7 100644
> --- a/drivers/media/platform/aspeed-video.c
> +++ b/drivers/media/platform/aspeed-video.c
> @@ -156,26 +156,22 @@
>  #define  VE_SRC_LR_EDGE_DET_NO_H       BIT(13)
>  #define  VE_SRC_LR_EDGE_DET_NO_DISP    BIT(14)
>  #define  VE_SRC_LR_EDGE_DET_NO_CLK     BIT(15)
> -#define  VE_SRC_LR_EDGE_DET_RT_SHF     16
> -#define  VE_SRC_LR_EDGE_DET_RT         GENMASK(27, VE_SRC_LR_EDGE_DET_RT_SHF)
> +#define  VE_SRC_LR_EDGE_DET_RT         GENMASK(27, 16)
>  #define  VE_SRC_LR_EDGE_DET_INTERLACE  BIT(31)
>
>  #define VE_SRC_TB_EDGE_DET             0x094
>  #define  VE_SRC_TB_EDGE_DET_TOP                GENMASK(12, 0)
> -#define  VE_SRC_TB_EDGE_DET_BOT_SHF    16
> -#define  VE_SRC_TB_EDGE_DET_BOT                GENMASK(28, VE_SRC_TB_EDGE_DET_BOT_SHF)
> +#define  VE_SRC_TB_EDGE_DET_BOT                GENMASK(28, 16)
>
>  #define VE_MODE_DETECT_STATUS          0x098
>  #define  VE_MODE_DETECT_H_PERIOD       GENMASK(11, 0)
> -#define  VE_MODE_DETECT_V_LINES_SHF    16
> -#define  VE_MODE_DETECT_V_LINES                GENMASK(27, VE_MODE_DETECT_V_LINES_SHF)
> +#define  VE_MODE_DETECT_V_LINES                GENMASK(27, 16)
>  #define  VE_MODE_DETECT_STATUS_VSYNC   BIT(28)
>  #define  VE_MODE_DETECT_STATUS_HSYNC   BIT(29)
>
>  #define VE_SYNC_STATUS                 0x09c
>  #define  VE_SYNC_STATUS_HSYNC          GENMASK(11, 0)
> -#define  VE_SYNC_STATUS_VSYNC_SHF      16
> -#define  VE_SYNC_STATUS_VSYNC          GENMASK(27, VE_SYNC_STATUS_VSYNC_SHF)
> +#define  VE_SYNC_STATUS_VSYNC          GENMASK(27, 16)
>
>  #define VE_H_TOTAL_PIXELS              0x0A0
>
> @@ -988,23 +984,24 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)
>                 sync = aspeed_video_read(video, VE_SYNC_STATUS);
>                 htotal = aspeed_video_read(video, VE_H_TOTAL_PIXELS);
>
> -               video->frame_bottom = (src_tb_edge & VE_SRC_TB_EDGE_DET_BOT) >>
> -                       VE_SRC_TB_EDGE_DET_BOT_SHF;
> -               video->frame_top = src_tb_edge & VE_SRC_TB_EDGE_DET_TOP;
> +               video->frame_bottom = FIELD_GET(VE_SRC_TB_EDGE_DET_BOT,
> +                                               src_tb_edge);
> +               video->frame_top = FIELD_GET(VE_SRC_TB_EDGE_DET_TOP,
> +                                            src_tb_edge);
>                 det->vfrontporch = video->frame_top;
> -               det->vbackporch = ((mds & VE_MODE_DETECT_V_LINES) >>
> -                       VE_MODE_DETECT_V_LINES_SHF) - video->frame_bottom;
> -               det->vsync = (sync & VE_SYNC_STATUS_VSYNC) >>
> -                       VE_SYNC_STATUS_VSYNC_SHF;
> +               det->vbackporch = FIELD_GET(VE_MODE_DETECT_V_LINES, mds) -
> +                       video->frame_bottom;
> +               det->vsync = FIELD_GET(VE_SYNC_STATUS_VSYNC, sync);
>                 if (video->frame_top > video->frame_bottom)
>                         continue;
>
> -               video->frame_right = (src_lr_edge & VE_SRC_LR_EDGE_DET_RT) >>
> -                       VE_SRC_LR_EDGE_DET_RT_SHF;
> -               video->frame_left = src_lr_edge & VE_SRC_LR_EDGE_DET_LEFT;
> +               video->frame_right = FIELD_GET(VE_SRC_LR_EDGE_DET_RT,
> +                                              src_lr_edge);
> +               video->frame_left = FIELD_GET(VE_SRC_LR_EDGE_DET_LEFT,
> +                                             src_lr_edge);

I suggest putting these on one line to further improve readability:

               video->frame_right = FIELD_GET(VE_SRC_LR_EDGE_DET_RT,
src_lr_edge);
               video->frame_left = FIELD_GET(VE_SRC_LR_EDGE_DET_LEFT,
src_lr_edge);

The same for the other lines you've changed above.

And then add:

Reviewed-by: Joel Stanley <joel@....id.au>

>                 det->hfrontporch = video->frame_left;
>                 det->hbackporch = htotal - video->frame_right;
> -               det->hsync = sync & VE_SYNC_STATUS_HSYNC;
> +               det->hsync = FIELD_GET(VE_SYNC_STATUS_HSYNC, sync);
>                 if (video->frame_left > video->frame_right)
>                         continue;
>
> --
> 2.25.1
>