Hi Rahul,
On 05/23/2014 04:19 AM, Rahul Sharma wrote:
> From: Rahul Sharma <Rahul.Sharma@xxxxxxxxxxx>
>
> Fimd probe is accessing fimd Registers without enabling the fimd
> gate clocks. If FIMD clocks are kept disabled in Uboot or disbaled
> during kernel boottime, the system hangs during boottime.
>
> This issue got surfaced when verifying with sysmmu enabled. Probe of
> fimd Sysmmu enables the master clock before accessing sysmmu regs and
> then disables. Later fimd probe tries to read the register without
> enabling the clock which is wrong and hangs the system.
>
> Signed-off-by: Rahul Sharma <Rahul.Sharma@xxxxxxxxxxx>
> ---
> v4:
> 1) Added clk_disable for prev clock when clk_enable fails.
> v3:
> 1) Added checks for clk_enable.
> v2:
> Rebase.
>
> drivers/gpu/drm/exynos/exynos_drm_fimd.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> index bd30d0c..30ccd67 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> @@ -898,16 +898,32 @@ static int fimd_bind(struct device *dev, struct device *master, void *data)
> {
> struct fimd_context *ctx = fimd_manager.ctx;
> struct drm_device *drm_dev = data;
> - int win;
> + int win, ret;
>
> fimd_mgr_initialize(&fimd_manager, drm_dev);
> exynos_drm_crtc_create(&fimd_manager);
> if (ctx->display)
> exynos_drm_create_enc_conn(drm_dev, ctx->display);
>
> + ret = clk_prepare_enable(ctx->bus_clk);
> + if (ret) {
> + dev_err(dev, "bus clock enable failed.\n");
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(ctx->lcd_clk);
> + if (ret) {
> + dev_err(dev, "lcd clock enable failed.\n");
> + clk_disable_unprepare(ctx->bus_clk);
> + return ret;
> + }
> +
> for (win = 0; win < WINDOWS_NR; win++)
> fimd_clear_win(ctx, win);
>
> + clk_disable_unprepare(ctx->lcd_clk);
> + clk_disable_unprepare(ctx->bus_clk);
> +
> return 0;
If you want to access fimd registers I guess pm_runtime_get_sync should
be called as well, to wake up display pm domain.
Regards
Andrzej
>
> }
>
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