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drm/ast: Acquire I/O-register lock in DDC code

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The modeset lock protects the DDC code from concurrent modeset
operations, which use the same registers. Move that code from the
connector helpers into the DDC helpers .pre_xfer() and .post_xfer().

Both, .pre_xfer() and .post_xfer(), enclose the transfer of data blocks
over the I2C channel in the internal I2C function bit_xfer(). Both
calls are executed unconditionally if present. Invoking DDC transfers
from any where within the driver now takes the lock.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Link: https://patchwork.freedesktop.org/patch/msgid/20240325200855.21150-11-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2024-03-25 21:06:55 +01:00
parent 660ed6ba8f
commit dfff99cb56
2 changed files with 28 additions and 26 deletions
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24
drivers/gpu/drm/ast/ast_ddc.c
View File

@ -59,6 +59,28 @@ static void ast_ddc_algo_bit_data_setscl(void *data, int state)
}
}
static int ast_ddc_algo_bit_data_pre_xfer(struct i2c_adapter *adapter)
{
struct ast_ddc *ddc = i2c_get_adapdata(adapter);
struct ast_device *ast = ddc->ast;
/*
* Protect access to I/O registers from concurrent modesetting
* by acquiring the I/O-register lock.
*/
mutex_lock(&ast->modeset_lock);
return 0;
}
static void ast_ddc_algo_bit_data_post_xfer(struct i2c_adapter *adapter)
{
struct ast_ddc *ddc = i2c_get_adapdata(adapter);
struct ast_device *ast = ddc->ast;
mutex_unlock(&ast->modeset_lock);
}
static int ast_ddc_algo_bit_data_getsda(void *data)
{
struct ast_ddc *ddc = data;
@ -137,6 +159,8 @@ struct ast_ddc *ast_ddc_create(struct ast_device *ast)
bit->setscl = ast_ddc_algo_bit_data_setscl;
bit->getsda = ast_ddc_algo_bit_data_getsda;
bit->getscl = ast_ddc_algo_bit_data_getscl;
bit->pre_xfer = ast_ddc_algo_bit_data_pre_xfer;
bit->post_xfer = ast_ddc_algo_bit_data_post_xfer;
adapter->algo_data = bit;
ret = i2c_bit_add_bus(adapter);

30
drivers/gpu/drm/ast/ast_mode.c
View File

@ -1346,30 +1346,19 @@ static int ast_crtc_init(struct drm_device *dev)
static int ast_vga_connector_helper_get_modes(struct drm_connector *connector)
{
struct drm_device *dev = connector->dev;
struct ast_device *ast = to_ast_device(dev);
struct edid *edid;
int count;
/*
* Protect access to I/O registers from concurrent modesetting
* by acquiring the I/O-register lock.
*/
mutex_lock(&ast->modeset_lock);
edid = drm_get_edid(connector, connector->ddc);
if (!edid)
goto err_mutex_unlock;
mutex_unlock(&ast->modeset_lock);
goto err_drm_get_edid;
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
err_mutex_unlock:
mutex_unlock(&ast->modeset_lock);
err_drm_get_edid:
drm_connector_update_edid_property(connector, NULL);
return 0;
}
@ -1444,30 +1433,19 @@ static int ast_vga_output_init(struct ast_device *ast)
static int ast_sil164_connector_helper_get_modes(struct drm_connector *connector)
{
struct drm_device *dev = connector->dev;
struct ast_device *ast = to_ast_device(dev);
struct edid *edid;
int count;
/*
* Protect access to I/O registers from concurrent modesetting
* by acquiring the I/O-register lock.
*/
mutex_lock(&ast->modeset_lock);
edid = drm_get_edid(connector, connector->ddc);
if (!edid)
goto err_mutex_unlock;
mutex_unlock(&ast->modeset_lock);
goto err_drm_get_edid;
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
err_mutex_unlock:
mutex_unlock(&ast->modeset_lock);
err_drm_get_edid:
drm_connector_update_edid_property(connector, NULL);
return 0;
}