Hi, Bibby:
On Fri, 2018-09-21 at 11:28 +0800, Bibby Hsieh wrote:
> From: chunhui dai <chunhui....@mediatek.com>
>
> After the kernel 4.4, the DRM disable flow was changed, if DPI was
> disableed before CRTC, it will cause warning message as following:
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1339 at
> ../../linux/linux-4.4.24-mtk/drivers/gpu/drm/drm_irq.c:1326
> drm_wait_one_vblank+0x188/0x18c()
> vblank wait timed out on crtc 0
> Modules linked in: bridge mt8521p_ir_shim(O) i2c_eeprom(O) mtk_m4(O)
> fuse_ctrl(O) virtual_block(O) caamkeys(PO) chk(PO) amperctl(O) ledctl(O)
> apple_auth(PO) micctl(O) sensors(PO) lla(O) sdd(PO) ice40_fpga(O) psmon(O)
> event_queue(PO) utils(O) blackbox(O)
> CPU: 0 PID: 1339 Comm: kworker/0:1 Tainted: P W O 4.4.24 #1
> Hardware name: Mediatek Cortex-A7 (Device Tree)
> Workqueue: events drm_mode_rmfb_work_fn
> [<c001a710>] (unwind_backtrace) from [<c00151e4>] (show_stack+0x20/0x24)
> [<c00151e4>] (show_stack) from [<c027961c>] (dump_stack+0x98/0xac)
> [<c027961c>] (dump_stack) from [<c002ac54>] (warn_slowpath_common+0x94/0xc4)
> [<c002ac54>] (warn_slowpath_common) from [<c002acc4>]
> (warn_slowpath_fmt+0x40/0x48)
> [<c002acc4>] (warn_slowpath_fmt) from [<c03307ac>]
> (drm_wait_one_vblank+0x188/0x18c)
> [<c03307ac>] (drm_wait_one_vblank) from [<c03307d8>]
> (drm_crtc_wait_one_vblank+0x28/0x2c)
> [<c03307d8>] (drm_crtc_wait_one_vblank) from [<c034f48c>]
> (mtk_drm_crtc_disable+0x78/0x240)
> [<c034f48c>] (mtk_drm_crtc_disable) from [<c03240d4>]
> (drm_atomic_helper_commit_modeset_disables+0x128/0x3b8)
> [<c03240d4>] (drm_atomic_helper_commit_modeset_disables) from [<c0350a7c>]
> (mtk_atomic_complete+0x74/0xb4)
> [<c0350a7c>] (mtk_atomic_complete) from [<c0350b24>]
> (mtk_atomic_commit+0x68/0x98)
> [<c0350b24>] (mtk_atomic_commit) from [<c034ab48>]
> (drm_atomic_commit+0x54/0x74)
> [<c034ab48>] (drm_atomic_commit) from [<c0325c4c>]
> (drm_atomic_helper_set_config+0x7c/0xa0)
> [<c0325c4c>] (drm_atomic_helper_set_config) from [<c0338594>]
> (drm_mode_set_config_internal+0x68/0xe4)
> [<c0338594>] (drm_mode_set_config_internal) from [<c033967c>]
> (drm_framebuffer_remove+0xe4/0x120)
> [<c033967c>] (drm_framebuffer_remove) from [<c0339700>]
> (drm_mode_rmfb_work_fn+0x48/0x58)
> [<c0339700>] (drm_mode_rmfb_work_fn) from [<c0043a38>]
> (process_one_work+0x154/0x50c)
> [<c0043a38>] (process_one_work) from [<c0044074>] (worker_thread+0x284/0x568)
> [<c0044074>] (worker_thread) from [<c0049dc4>] (kthread+0xec/0x104)
> [<c0049dc4>] (kthread) from [<c0010678>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 12ae5358e992abd5 ]---
>
> so, we add refcount for DPI power on/off to protect the flow.
>
> Signed-off-by: Bibby Hsieh <bibby.hs...@mediatek.com>
> Signed-off-by: chunhui dai <chunhui....@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_dpi.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 6c0ea39d5739..d9373e67d328 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -77,6 +77,7 @@ struct mtk_dpi {
> enum mtk_dpi_out_bit_num bit_num;
> enum mtk_dpi_out_channel_swap channel_swap;
> bool power_sta;
> + int refcount;
> u8 power_ctl;
> };
>
> @@ -369,6 +370,12 @@ static void mtk_dpi_config_color_format(struct mtk_dpi
> *dpi,
>
> static void mtk_dpi_power_off(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl
> pctl)
> {
> + if (WARN_ON(dpi->refcount == 0))
> + return;
> +
> + if (--dpi->refcount != 0)
> + return;
> +
> dpi->power_ctl &= ~pctl;
>
> if ((dpi->power_ctl & DPI_POWER_START) ||
> @@ -388,14 +395,17 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum
> mtk_dpi_power_ctl pctl)
> {
> int ret;
>
> + if (++dpi->refcount != 1)
> + return 0;
> +
> dpi->power_ctl |= pctl;
>
> if (!(dpi->power_ctl & DPI_POWER_START) &&
> !(dpi->power_ctl & DPI_POWER_ENABLE))
> - return 0;
> + goto err_refcount;
>
> if (dpi->power_sta)
> - return 0;
> + goto err_refcount;
I think dpi->power_ctl and dpi->power_sta is something like reference
count. mtk_dpi_start() and mtk_dpi_stop() is called by crtc. If the
error message happen without this patch, I think there is a bug in
dpi->power_ctl and dpi->power_sta. I think you should fix the bug of
dpi->power_ctl and dpi->power_sta, or just replace it with your
reference count mechanism.
Regards,
CK
>
> ret = clk_prepare_enable(dpi->engine_clk);
> if (ret) {
> @@ -417,6 +427,8 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum
> mtk_dpi_power_ctl pctl)
> clk_disable_unprepare(dpi->engine_clk);
> err_eng:
> dpi->power_ctl &= ~pctl;
> +err_refcount:
> + dpi->refcount--;
> return ret;
> }
>
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