Re: [PATCH v5 4/9] drm/mediatek: dsi: Use bitfield macros where useful

From: CK Hu (胡俊光)
Date: Thu Feb 15 2024 - 02:33:55 EST

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Hi, Angelo:

On Wed, 2024-02-07 at 15:53 +0100, AngeloGioacchino Del Regno wrote:
> Instead of open coding bitshifting for various register fields,
> use the bitfield macro FIELD_PREP(): this allows to enhance the
> human readability, decrease likeliness of mistakes (and register
> field overflowing) and also to simplify the code.
> The latter is especially seen in mtk_dsi_rxtx_control(), where
> it was possible to change a switch to a short for loop and to
> also remove the need to check for maximum DSI lanes == 4 thanks
> to the FIELD_PREP macro masking the value.
>
> While at it, also add the missing DA_HS_SYNC bitmask, used in
> mtk_dsi_phy_timconfig().
>
> Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/mediatek/mtk_dsi.c | 97 ++++++++++++++++----------
> ----
> 1 file changed, 52 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 7d38e9500700..a330bb94c44a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -3,6 +3,7 @@
> * Copyright (c) 2015 MediaTek Inc.
> */
>
> +#include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/component.h>
> #include <linux/iopoll.h>
> @@ -70,16 +71,19 @@
> #define DSI_PSCTRL 0x1c
> #define DSI_PS_WC GENMASK(13, 0)
> #define DSI_PS_SEL GENMASK(17, 16)
> -#define PACKED_PS_16BIT_RGB565 (0 << 16)
> -#define PACKED_PS_18BIT_RGB666 (1 << 16)
> -#define LOOSELY_PS_24BIT_RGB666 (2 << 16)
> -#define PACKED_PS_24BIT_RGB888 (3 << 16)
> +#define PACKED_PS_16BIT_RGB565 0
> +#define PACKED_PS_18BIT_RGB666 1
> +#define LOOSELY_PS_24BIT_RGB666 2
> +#define PACKED_PS_24BIT_RGB888 3
>
> #define DSI_VSA_NL 0x20
> #define DSI_VBP_NL 0x24
> #define DSI_VFP_NL 0x28
> #define DSI_VACT_NL 0x2C
> +#define VACT_NL GENMASK(14, 0)
> #define DSI_SIZE_CON 0x38
> +#define DSI_HEIGHT GENMASK(30, 16)
> +#define DSI_WIDTH GENMASK(14, 0)
> #define DSI_HSA_WC 0x50
> #define DSI_HBP_WC 0x54
> #define DSI_HFP_WC 0x58
> @@ -122,6 +126,7 @@
>
> #define DSI_PHY_TIMECON2 0x118
> #define CONT_DET GENMASK(7, 0)
> +#define DA_HS_SYNC GENMASK(15, 8)
> #define CLK_ZERO GENMASK(23, 16)
> #define CLK_TRAIL GENMASK(31, 24)
>
> @@ -253,14 +258,23 @@ static void mtk_dsi_phy_timconfig(struct
> mtk_dsi *dsi)
> timing->clk_hs_zero = timing->clk_hs_trail * 4;
> timing->clk_hs_exit = 2 * timing->clk_hs_trail;
>
> - timcon0 = timing->lpx | timing->da_hs_prepare << 8 |
> - timing->da_hs_zero << 16 | timing->da_hs_trail << 24;
> - timcon1 = timing->ta_go | timing->ta_sure << 8 |
> - timing->ta_get << 16 | timing->da_hs_exit << 24;
> - timcon2 = 1 << 8 | timing->clk_hs_zero << 16 |
> - timing->clk_hs_trail << 24;
> - timcon3 = timing->clk_hs_prepare | timing->clk_hs_post << 8 |
> - timing->clk_hs_exit << 16;
> + timcon0 = FIELD_PREP(LPX, timing->lpx) |
> + FIELD_PREP(HS_PREP, timing->da_hs_prepare) |
> + FIELD_PREP(HS_ZERO, timing->da_hs_zero) |
> + FIELD_PREP(HS_TRAIL, timing->da_hs_trail);
> +
> + timcon1 = FIELD_PREP(TA_GO, timing->ta_go) |
> + FIELD_PREP(TA_SURE, timing->ta_sure) |
> + FIELD_PREP(TA_GET, timing->ta_get) |
> + FIELD_PREP(DA_HS_EXIT, timing->da_hs_exit);
> +
> + timcon2 = FIELD_PREP(DA_HS_SYNC, 1) |
> + FIELD_PREP(CLK_ZERO, timing->clk_hs_zero) |
> + FIELD_PREP(CLK_TRAIL, timing->clk_hs_trail);
> +
> + timcon3 = FIELD_PREP(CLK_HS_PREP, timing->clk_hs_prepare) |
> + FIELD_PREP(CLK_HS_POST, timing->clk_hs_post) |
> + FIELD_PREP(CLK_HS_EXIT, timing->clk_hs_exit);
>
> writel(timcon0, dsi->regs + DSI_PHY_TIMECON0);
> writel(timcon1, dsi->regs + DSI_PHY_TIMECON1);
> @@ -353,69 +367,61 @@ static void mtk_dsi_set_vm_cmd(struct mtk_dsi
> *dsi)
>
> static void mtk_dsi_rxtx_control(struct mtk_dsi *dsi)
> {
> - u32 tmp_reg;
> + u32 regval, tmp_reg = 0;
> + u8 i;
>
> - switch (dsi->lanes) {
> - case 1:
> - tmp_reg = 1 << 2;
> - break;
> - case 2:
> - tmp_reg = 3 << 2;
> - break;
> - case 3:
> - tmp_reg = 7 << 2;
> - break;
> - case 4:
> - tmp_reg = 0xf << 2;
> - break;
> - default:
> - tmp_reg = 0xf << 2;
> - break;
> - }
> + /* Number of DSI lanes (max 4 lanes), each bit enables one DSI
> lane. */
> + for (i = 0; i < dsi->lanes; i++)
> + tmp_reg |= BIT(i);
> +
> + regval = FIELD_PREP(LANE_NUM, tmp_reg);
>
> if (dsi->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS)
> - tmp_reg |= HSTX_CKLP_EN;
> + regval |= HSTX_CKLP_EN;
>
> if (dsi->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
> - tmp_reg |= DIS_EOT;
> + regval |= DIS_EOT;
>
> - writel(tmp_reg, dsi->regs + DSI_TXRX_CTRL);
> + writel(regval, dsi->regs + DSI_TXRX_CTRL);
> }
>
> static void mtk_dsi_ps_control(struct mtk_dsi *dsi, bool
> config_vact)
> {
> - struct videomode *vm = &dsi->vm;
> - u32 dsi_buf_bpp, ps_wc;
> - u32 ps_bpp_mode;
> + u32 dsi_buf_bpp, ps_val, ps_wc, vact_nl;
>
> if (dsi->format == MIPI_DSI_FMT_RGB565)
> dsi_buf_bpp = 2;
> else
> dsi_buf_bpp = 3;
>
> - ps_wc = vm->hactive * dsi_buf_bpp;
> - ps_bpp_mode = ps_wc;
> + /* Word count */
> + ps_wc = FIELD_PREP(DSI_PS_WC, dsi->vm.hactive * dsi_buf_bpp);
> + ps_val = ps_wc;
>
> + /* Pixel Stream type */
> switch (dsi->format) {
> + default:
> + fallthrough;

This is not related to bitfield macro. You remove default in previous
patch but add it back in this patch. I think this should be moved to
previous patch. After this change,

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

> case MIPI_DSI_FMT_RGB888:
> - ps_bpp_mode |= PACKED_PS_24BIT_RGB888;
> + ps_val |= FIELD_PREP(DSI_PS_SEL,
> PACKED_PS_24BIT_RGB888);
> break;
> case MIPI_DSI_FMT_RGB666:
> - ps_bpp_mode |= LOOSELY_PS_24BIT_RGB666;
> + ps_val |= FIELD_PREP(DSI_PS_SEL,
> LOOSELY_PS_24BIT_RGB666);
> break;
> case MIPI_DSI_FMT_RGB666_PACKED:
> - ps_bpp_mode |= PACKED_PS_18BIT_RGB666;
> + ps_val |= FIELD_PREP(DSI_PS_SEL,
> PACKED_PS_18BIT_RGB666);
> break;
> case MIPI_DSI_FMT_RGB565:
> - ps_bpp_mode |= PACKED_PS_16BIT_RGB565;
> + ps_val |= FIELD_PREP(DSI_PS_SEL,
> PACKED_PS_16BIT_RGB565);
> break;
> }
>
> if (config_vact) {
> - writel(vm->vactive, dsi->regs + DSI_VACT_NL);
> + vact_nl = FIELD_PREP(VACT_NL, dsi->vm.vactive);
> + writel(vact_nl, dsi->regs + DSI_VACT_NL);
> writel(ps_wc, dsi->regs + DSI_HSTX_CKL_WC);
> }
> - writel(ps_bpp_mode, dsi->regs + DSI_PSCTRL);
> + writel(ps_val, dsi->regs + DSI_PSCTRL);
> }
>
> static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
> @@ -442,7 +448,8 @@ static void mtk_dsi_config_vdo_timing(struct
> mtk_dsi *dsi)
> writel(vm->vactive, dsi->regs + DSI_VACT_NL);
>
> if (dsi->driver_data->has_size_ctl)
> - writel(vm->vactive << 16 | vm->hactive,
> + writel(FIELD_PREP(DSI_HEIGHT, vm->vactive) |
> + FIELD_PREP(DSI_WIDTH, vm->hactive),
> dsi->regs + DSI_SIZE_CON);
>
> horizontal_sync_active_byte = (vm->hsync_len * dsi_tmp_buf_bpp
> - 10);

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