[PATCH 2/2] drm/exynos: dsi: add LPM (Low Power Mode) transfer support

[Inki Dae]

This patch adds LPM transfer support for video or command data.

With this patch, Exynos MIPI DSI controller can transfer command or
video data with HS or LP mode in accordance with mode_flags set
by LCD Panel driver.

Signed-off-by: Inki Dae <inki.dae at samsung.com>
Acked-by: Kyungmin Park <kyungmin.park at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_dsi.c |   22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c 
b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 2df3592..b120554 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -426,13 +426,28 @@ static int exynos_dsi_enable_clock(struct exynos_dsi *dsi)
                        | DSIM_ESC_PRESCALER(esc_div)
                        | DSIM_LANE_ESC_CLK_EN_CLK
                        | DSIM_LANE_ESC_CLK_EN_DATA(BIT(dsi->lanes) - 1)
-                       | DSIM_BYTE_CLK_SRC(0)
-                       | DSIM_TX_REQUEST_HSCLK;
+                       | DSIM_BYTE_CLK_SRC(0);
+
+       if (!(dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM))
+               reg |= DSIM_TX_REQUEST_HSCLK;
+
        writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);

        return 0;
 }

+static void exynos_dsi_enable_hs_clock(struct exynos_dsi *dsi,
+                                       bool enable)
+{
+       u32 reg = readl(dsi->reg_base + DSIM_CLKCTRL_REG);
+
+       reg &= ~DSIM_TX_REQUEST_HSCLK;
+       if (enable)
+               reg |= DSIM_TX_REQUEST_HSCLK;
+
+       writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
+}
+
 static void exynos_dsi_disable_clock(struct exynos_dsi *dsi)
 {
        u32 reg;
@@ -575,6 +590,9 @@ static void exynos_dsi_set_display_enable(struct exynos_dsi 
*dsi, bool enable)
 {
        u32 reg;

+       if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_LPM))
+               exynos_dsi_enable_hs_clock(dsi, true);
+
        reg = readl(dsi->reg_base + DSIM_MDRESOL_REG);
        if (enable)
                reg |= DSIM_MAIN_STAND_BY;
-- 
1.7.9.5