Am 03.04.24 um 11:02 schrieb Jammy Huang:
There is a while-loop in ast_dp_set_on_off() that could lead to infinite-loop. This is because the register, VGACRI-Dx, checked in this API is a scratch register actually controlled by a MCU, named DPMCU, in BMC. These scratch registers are protected by scu-lock. If suc-lock is not off, DPMCU can not update these registers and then host will have soft lockup due to never updated status. DPMCU is used to control DP and relative registers to handshake with host's VGA driver. Even the most time-consuming task, DP's link training, is less than 100ms. 200ms should be enough. Signed-off-by: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx> Reviewed-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
--- drivers/gpu/drm/ast/ast_dp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c index ebb6d8ebd44e..1e9259416980 100644 --- a/drivers/gpu/drm/ast/ast_dp.c +++ b/drivers/gpu/drm/ast/ast_dp.c @@ -180,6 +180,7 @@ void ast_dp_set_on_off(struct drm_device *dev, bool on) { struct ast_device *ast = to_ast_device(dev); u8 video_on_off = on; + u32 i = 0;// Video On/Offast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xE3, (u8) ~AST_DP_VIDEO_ENABLE, on); @@ -192,6 +193,8 @@ void ast_dp_set_on_off(struct drm_device *dev, bool on) ASTDP_MIRROR_VIDEO_ENABLE) != video_on_off) { // wait 1 ms mdelay(1); + if (++i > 200) + break; } } } base-commit: b0546776ad3f332e215cebc0b063ba4351971cca
-- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)
