From 3534401df2c04d2e0e900ebcbdec51c0dfe12f67 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Mon, 2 May 2022 16:25:13 +0200
Subject: drm/ast: Protect concurrent access to I/O registers with lock
Git-commit: f870231fdd6ce2c6c040a3584a2eac97ae473780
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
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 register AST_IO_CRTC_PORT. Concurrent access can lead to
failed mode-setting operations.
v2:
* fix typo in commit description (Jocelyn)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reported-by: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220502142514.2174-3-tzimmermann@suse.de
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/ast/ast_drv.h | 1 +
drivers/gpu/drm/ast/ast_main.c | 4 +++
drivers/gpu/drm/ast/ast_mode.c | 48 +++++++++++++++++++++++++++++++---
3 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
index ff1ae314bd0d..afebe35f205e 100644
--- a/drivers/gpu/drm/ast/ast_drv.h
+++ b/drivers/gpu/drm/ast/ast_drv.h
@@ -159,6 +159,7 @@ to_ast_sil164_connector(struct drm_connector *connector)
struct ast_private {
struct drm_device base;
+ struct mutex ioregs_lock; /* Protects access to I/O registers in ioregs */
void __iomem *regs;
void __iomem *ioregs;
void __iomem *dp501_fw_buf;
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 1113ee1cb7d4..d770d5a23c1a 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -421,6 +421,10 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
pci_set_drvdata(pdev, dev);
+ ret = drmm_mutex_init(dev, &ast->ioregs_lock);
+ if (ret)
+ return ERR_PTR(ret);
+
ast->regs = pcim_iomap(pdev, 1, 0);
if (!ast->regs)
return ERR_PTR(-EIO);
diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 4728825b7b67..323af2746aa9 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1119,6 +1119,20 @@ static int ast_crtc_helper_atomic_check(struct drm_crtc *crtc,
return 0;
}
+static void ast_crtc_helper_atomic_begin(struct drm_crtc *crtc, struct drm_atomic_state *state)
+{
+ struct drm_device *dev = crtc->dev;
+ struct ast_private *ast = to_ast_private(dev);
+
+ /*
+ * 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. Released in atomic_flush().
+ */
+ mutex_lock(&ast->ioregs_lock);
+}
+
static void
ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
struct drm_atomic_state *state)
@@ -1127,7 +1141,8 @@ ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
crtc);
struct drm_crtc_state *old_crtc_state = drm_atomic_get_old_crtc_state(state,
crtc);
- struct ast_private *ast = to_ast_private(crtc->dev);
+ struct drm_device *dev = crtc->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct ast_crtc_state *ast_crtc_state = to_ast_crtc_state(crtc_state);
struct ast_crtc_state *old_ast_crtc_state = to_ast_crtc_state(old_crtc_state);
struct ast_vbios_mode_info *vbios_mode_info = &ast_crtc_state->vbios_mode_info;
@@ -1142,6 +1157,8 @@ ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
//Set Aspeed Display-Port
if (ast->tx_chip_type == AST_TX_ASTDP)
ast_dp_set_mode(crtc, vbios_mode_info);
+
+ mutex_unlock(&ast->ioregs_lock);
}
static void
@@ -1200,6 +1217,7 @@ ast_crtc_helper_atomic_disable(struct drm_crtc *crtc,
static const struct drm_crtc_helper_funcs ast_crtc_helper_funcs = {
.mode_valid = ast_crtc_helper_mode_valid,
.atomic_check = ast_crtc_helper_atomic_check,
+ .atomic_begin = ast_crtc_helper_atomic_begin,
.atomic_flush = ast_crtc_helper_atomic_flush,
.atomic_enable = ast_crtc_helper_atomic_enable,
.atomic_disable = ast_crtc_helper_atomic_disable,
@@ -1285,21 +1303,33 @@ static int ast_crtc_init(struct drm_device *dev)
static int ast_vga_connector_helper_get_modes(struct drm_connector *connector)
{
struct ast_vga_connector *ast_vga_connector = to_ast_vga_connector(connector);
+ struct drm_device *dev = connector->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct edid *edid;
int count;
if (!ast_vga_connector->i2c)
goto err_drm_connector_update_edid_property;
+ /*
+ * Protect access to I/O registers from concurrent modesetting
+ * by acquiring the I/O-register lock.
+ */
+ mutex_lock(&ast->ioregs_lock);
+
edid = drm_get_edid(connector, &ast_vga_connector->i2c->adapter);
if (!edid)
- goto err_drm_connector_update_edid_property;
+ goto err_mutex_unlock;
+
+ mutex_unlock(&ast->ioregs_lock);
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
+err_mutex_unlock:
+ mutex_unlock(&ast->ioregs_lock);
err_drm_connector_update_edid_property:
drm_connector_update_edid_property(connector, NULL);
return 0;
@@ -1379,21 +1409,33 @@ static int ast_vga_output_init(struct ast_private *ast)
static int ast_sil164_connector_helper_get_modes(struct drm_connector *connector)
{
struct ast_sil164_connector *ast_sil164_connector = to_ast_sil164_connector(connector);
+ struct drm_device *dev = connector->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct edid *edid;
int count;
if (!ast_sil164_connector->i2c)
goto err_drm_connector_update_edid_property;
+ /*
+ * Protect access to I/O registers from concurrent modesetting
+ * by acquiring the I/O-register lock.
+ */
+ mutex_lock(&ast->ioregs_lock);
+
edid = drm_get_edid(connector, &ast_sil164_connector->i2c->adapter);
if (!edid)
- goto err_drm_connector_update_edid_property;
+ goto err_mutex_unlock;
+
+ mutex_unlock(&ast->ioregs_lock);
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
+err_mutex_unlock:
+ mutex_unlock(&ast->ioregs_lock);
err_drm_connector_update_edid_property:
drm_connector_update_edid_property(connector, NULL);
return 0;
--
2.38.1