The patch below does not apply to the 4.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ae9d04214372a521e3746556eb2f76007d9edb73 Mon Sep 17 00:00:00 2001 From: Fabio Estevam <fabio.estevam@xxxxxxx> Date: Fri, 5 May 2017 15:01:41 -0300 Subject: [PATCH] drm: mxsfb_crtc: Reset the eLCDIF controller According to the eLCDIF initialization steps listed in the MX6SX Reference Manual the eLCDIF block reset is mandatory. Without performing the eLCDIF reset the display shows garbage content when the kernel boots. In earlier tests this issue has not been observed because the bootloader was previously showing a splash screen and the bootloader display driver does properly implement the eLCDIF reset. Add the eLCDIF reset to the driver, so that it can operate correctly independently of the bootloader. Tested on a imx6sx-sdb board. Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxx> Reviewed-by: Marek Vasut <marex@xxxxxxx> Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/1494007301-14535-1-git-send-email-fabio.estevam@xxxxxxx diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c index 1144e0c9e894..0abe77675b76 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c @@ -35,6 +35,13 @@ #include "mxsfb_drv.h" #include "mxsfb_regs.h" +#define MXS_SET_ADDR 0x4 +#define MXS_CLR_ADDR 0x8 +#define MODULE_CLKGATE BIT(30) +#define MODULE_SFTRST BIT(31) +/* 1 second delay should be plenty of time for block reset */ +#define RESET_TIMEOUT 1000000 + static u32 set_hsync_pulse_width(struct mxsfb_drm_private *mxsfb, u32 val) { return (val & mxsfb->devdata->hs_wdth_mask) << @@ -159,6 +166,36 @@ static void mxsfb_disable_controller(struct mxsfb_drm_private *mxsfb) clk_disable_unprepare(mxsfb->clk_disp_axi); } +/* + * Clear the bit and poll it cleared. This is usually called with + * a reset address and mask being either SFTRST(bit 31) or CLKGATE + * (bit 30). + */ +static int clear_poll_bit(void __iomem *addr, u32 mask) +{ + u32 reg; + + writel(mask, addr + MXS_CLR_ADDR); + return readl_poll_timeout(addr, reg, !(reg & mask), 0, RESET_TIMEOUT); +} + +static int mxsfb_reset_block(void __iomem *reset_addr) +{ + int ret; + + ret = clear_poll_bit(reset_addr, MODULE_SFTRST); + if (ret) + return ret; + + writel(MODULE_CLKGATE, reset_addr + MXS_CLR_ADDR); + + ret = clear_poll_bit(reset_addr, MODULE_SFTRST); + if (ret) + return ret; + + return clear_poll_bit(reset_addr, MODULE_CLKGATE); +} + static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb) { struct drm_display_mode *m = &mxsfb->pipe.crtc.state->adjusted_mode; @@ -173,6 +210,11 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb) */ mxsfb_enable_axi_clk(mxsfb); + /* Mandatory eLCDIF reset as per the Reference Manual */ + err = mxsfb_reset_block(mxsfb->base); + if (err) + return; + /* Clear the FIFOs */ writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);