Re: [PATCH v3] drm/exynos: dsi: check whether dsi is enabled before sending data

[Inki Dae <inki.dae@samsung.com>]

On 2015년 06월 09일 12:19, Hyungwon Hwang wrote:
> exynos_dsi_host_transfer() can be called through a panel driver while
> DSI is turning down. It is possible because the function checks only
> whether DSI is initialized or not, and there is a moment which DSI is
> set by uninitialized, but DSI is still turning down. To prevent it,
> DSI must be set by disabled before starting to be turned down, and
> exynos_dsi_host_transfer() must check whether DSI is enabled or not.

Applied.

Thanks,
Inki Dae

> 
> Kernel dump:
> [ 4721.351448] Unhandled fault: synchronous external abort (0x96000210) at 0xffffff800015e018
> [ 4721.351809] Internal error: : 96000210 [#1] PREEMPT SMP
> [ 4721.352031] Modules linked in:
> [ 4721.352173] CPU: 2 PID: 300 Comm: deviced Tainted: G        W       4.0.4-01017-g7964a87 #1
> [ 4721.353989] Hardware name: Samsung DRACO board (DT)
> [ 4721.358852] task: ffffffc0a0b70000 ti: ffffffc0a00ec000 task.ti: ffffffc0a00ec000
> [ 4721.366327] PC is at exynos_dsi_enable_lane+0x14/0x5c
> [ 4721.371353] LR is at exynos_dsi_host_transfer+0x834/0x8d8
> [ 4721.376731] pc : [<ffffffc000432bcc>] lr : [<ffffffc000434590>] pstate: 60000145
> [ 4721.384107] sp : ffffffc0a00efbe0
> [ 4721.387405] x29: ffffffc0a00efbe0 x28: ffffffc0a00ec000
> [ 4721.392699] x27: ffffffc000968000 x26: 0000000000000040
> [ 4721.397994] x25: ffffffc000f74dc0 x24: ffffffc0a00efec8
> [ 4721.403290] x23: ffffffc0a4815400 x22: ffffffc0009f2729
> [ 4721.408584] x21: ffffffc0a00efcc8 x20: ffffffc0a4a2a848
> [ 4721.413879] x19: ffffffc0a4a2a818 x18: 0000000000000004
> [ 4721.419173] x17: 0000007faa5cddf0 x16: ffffffc0001a40a8
> [ 4721.424469] x15: 0000000000000009 x14: 000000000000000d
> [ 4721.429762] x13: 6e6e6f63206b726f x12: 0000000000000010
> [ 4721.435058] x11: 0101010101010101 x10: 0000000000000000
> [ 4721.440353] x9 : 000000000000000a x8 : 8386838282818381
> [ 4721.445648] x7 : ffffffc0a201efe8 x6 : 0000000000000000
> [ 4721.450943] x5 : 00000000fffffffa x4 : ffffffc0a201f170
> [ 4721.456237] x3 : ffffff800015e000 x2 : ffffff800015e018
> [ 4721.461531] x1 : 000000000000000f x0 : ffffffc0a4a2a818
> [ 4721.466826]
> [ 4721.468305] Process deviced (pid: 300, stack limit = 0xffffffc0a00ec028)
> [ 4721.474989] Stack: (0xffffffc0a00efbe0 to 0xffffffc0a00f0000)
> [ 4721.480720] fbe0: a00efca0 ffffffc0 0042c944 ffffffc0 a0f2d680 ffffffc0 00000024 00000000
> [ 4721.488895] fc00: a4b6d000 ffffffc0 009f2729 ffffffc0 a4815400 ffffffc0 a00efec8 ffffffc0
> 
> Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>
> ---
> Changes for v2:
>  - Previous version of this patch makes a problem in initializing the DSI. This
>    patch fixes it, by moving the point which DSI is set by enabled to the
>    point before drm_panel_prepare() called. This is where the setting must
>    be done, because to call drm_panel_prepare() successfully, DSI must be
>    enabled. Also this patch adds the condition to TE irq handler. DSI must be
>    enabled and initialized, not just enabled before calling te_handler in
>    the display driver.
> Changes for v3:
>  - New state DSIM_STATE_VIDOUT_AVAILABLE for representing video output
>    availability is introduced. Because DSIM_STATE_ENABLED becomes to
>    represent whether DSI can be used for data transfer or not, this
>    state can be used for checking whether video ouput is available or
>    not anymore. So new state have to be introduced. The stete
>    DSIM_STATE_VIDOUT_AVAILABLE represents whether DSI is prepared for
>    outputting video to a panel or not.
> 
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 1cfc4be07..9250356 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -241,6 +241,7 @@ struct exynos_dsi_transfer {
>  #define DSIM_STATE_ENABLED		BIT(0)
>  #define DSIM_STATE_INITIALIZED		BIT(1)
>  #define DSIM_STATE_CMD_LPM		BIT(2)
> +#define DSIM_STATE_VIDOUT_AVAILABLE	BIT(3)
> 
>  struct exynos_dsi_driver_data {
>  	unsigned int *regs;
> @@ -1268,7 +1269,7 @@ static irqreturn_t exynos_dsi_te_irq_handler(int irq, void *dev_id)
>  	struct exynos_dsi *dsi = (struct exynos_dsi *)dev_id;
>  	struct drm_encoder *encoder = dsi->display.encoder;
> 
> -	if (dsi->state & DSIM_STATE_ENABLED)
> +	if (dsi->state & DSIM_STATE_VIDOUT_AVAILABLE)
>  		exynos_drm_crtc_te_handler(encoder->crtc);
> 
>  	return IRQ_HANDLED;
> @@ -1408,6 +1409,9 @@ static ssize_t exynos_dsi_host_transfer(struct mipi_dsi_host *host,
>  	struct exynos_dsi_transfer xfer;
>  	int ret;
> 
> +	if (!(dsi->state & DSIM_STATE_ENABLED))
> +		return -EINVAL;
> +
>  	if (!(dsi->state & DSIM_STATE_INITIALIZED)) {
>  		ret = exynos_dsi_init(dsi);
>  		if (ret)
> @@ -1520,8 +1524,11 @@ static int exynos_dsi_enable(struct exynos_dsi *dsi)
>  	if (ret < 0)
>  		return ret;
> 
> +	dsi->state |= DSIM_STATE_ENABLED;
> +
>  	ret = drm_panel_prepare(dsi->panel);
>  	if (ret < 0) {
> +		dsi->state &= ~DSIM_STATE_ENABLED;
>  		exynos_dsi_poweroff(dsi);
>  		return ret;
>  	}
> @@ -1529,8 +1536,6 @@ static int exynos_dsi_enable(struct exynos_dsi *dsi)
>  	exynos_dsi_set_display_mode(dsi);
>  	exynos_dsi_set_display_enable(dsi, true);
> 
> -	dsi->state |= DSIM_STATE_ENABLED;
> -
>  	ret = drm_panel_enable(dsi->panel);
>  	if (ret < 0) {
>  		dsi->state &= ~DSIM_STATE_ENABLED;
> @@ -1540,6 +1545,8 @@ static int exynos_dsi_enable(struct exynos_dsi *dsi)
>  		return ret;
>  	}
> 
> +	dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
> +
>  	return 0;
>  }
> 
> @@ -1548,12 +1555,15 @@ static void exynos_dsi_disable(struct exynos_dsi *dsi)
>  	if (!(dsi->state & DSIM_STATE_ENABLED))
>  		return;
> 
> +	dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE;
> +
>  	drm_panel_disable(dsi->panel);
>  	exynos_dsi_set_display_enable(dsi, false);
>  	drm_panel_unprepare(dsi->panel);
> -	exynos_dsi_poweroff(dsi);
> 
>  	dsi->state &= ~DSIM_STATE_ENABLED;
> +
> +	exynos_dsi_poweroff(dsi);
>  }
> 
>  static void exynos_dsi_dpms(struct exynos_drm_display *display, int mode)
> --
> 1.9.1
> 
> 

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