From 931e3f3a0e997c41eafbc88e4fc07ba9fef28f29 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Mon, 2 May 2022 16:25:14 +0200 Subject: [PATCH] drm/mgag200: Protect concurrent access to I/O registers with lock Add a mutex lock to protect concurrent access to I/O registers against each other. This happens between invocation of commit- tail functions and get-mode operations. Both with use the CRTC index registers MGA1064_GEN_IO_DATA and MGA1064_GEN_IO_CTL. Concurrent access can lead to failed mode-setting operations. v2: * fix typo in commit description (Jocelyn) * add comment to explain rmmio_lock Signed-off-by: Thomas Zimmermann Reviewed-by: Jocelyn Falempe Acked-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220502142514.2174-4-tzimmermann@suse.de --- drivers/gpu/drm/mgag200/mgag200_drv.c | 6 ++++++ drivers/gpu/drm/mgag200/mgag200_drv.h | 1 + drivers/gpu/drm/mgag200/mgag200_mode.c | 14 ++++++++++++++ 3 files changed, 21 insertions(+) diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c index 217844d71ab5..08839460606f 100644 --- a/drivers/gpu/drm/mgag200/mgag200_drv.c +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -65,6 +66,11 @@ static int mgag200_regs_init(struct mga_device *mdev) struct pci_dev *pdev = to_pci_dev(dev->dev); u32 option, option2; u8 crtcext3; + int ret; + + ret = drmm_mutex_init(dev, &mdev->rmmio_lock); + if (ret) + return ret; switch (mdev->type) { case G200_PCI: diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h index 4368112023f7..a18384c41fc4 100644 --- a/drivers/gpu/drm/mgag200/mgag200_drv.h +++ b/drivers/gpu/drm/mgag200/mgag200_drv.h @@ -213,6 +213,7 @@ struct mga_device { struct drm_device base; unsigned long flags; + struct mutex rmmio_lock; /* Protects access to rmmio */ resource_size_t rmmio_base; resource_size_t rmmio_size; void __iomem *rmmio; diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index 6e18d3bbd720..abde7655477d 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -881,6 +881,14 @@ mgag200_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe, .y2 = fb->height, }; + /* + * Concurrent operations could possibly trigger a call to + * drm_connector_helper_funcs.get_modes by trying to read the + * display modes. Protect access to I/O registers by acquiring + * the I/O-register lock. + */ + mutex_lock(&mdev->rmmio_lock); + if (mdev->type == G200_WB || mdev->type == G200_EW3) mgag200_g200wb_hold_bmc(mdev); @@ -904,6 +912,8 @@ mgag200_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe, mgag200_enable_display(mdev); mgag200_handle_damage(mdev, fb, &fullscreen, &shadow_plane_state->data[0]); + + mutex_unlock(&mdev->rmmio_lock); } static void @@ -963,8 +973,12 @@ mgag200_simple_display_pipe_update(struct drm_simple_display_pipe *pipe, if (!fb) return; + mutex_lock(&mdev->rmmio_lock); + if (drm_atomic_helper_damage_merged(old_state, state, &damage)) mgag200_handle_damage(mdev, fb, &damage, &shadow_plane_state->data[0]); + + mutex_unlock(&mdev->rmmio_lock); } static struct drm_crtc_state * -- 2.11.0