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drm/mgag200: 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: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240513125620.6337-10-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann
2024-05-13 14:51:14 +02:00
parent b7e04af37e
commit 66d58ec0bc
2 changed files with 24 additions and 9 deletions
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24
drivers/gpu/drm/mgag200/mgag200_ddc.c
View File

@@ -99,6 +99,28 @@ static int mgag200_ddc_algo_bit_data_getscl(void *data)
return (mga_i2c_read_gpio(ddc->mdev) & ddc->clock) ? 1 : 0;
}
static int mgag200_ddc_algo_bit_data_pre_xfer(struct i2c_adapter *adapter)
{
struct mgag200_ddc *ddc = i2c_get_adapdata(adapter);
struct mga_device *mdev = ddc->mdev;
/*
* Protect access to I/O registers from concurrent modesetting
* by acquiring the I/O-register lock.
*/
mutex_lock(&mdev->rmmio_lock);
return 0;
}
static void mgag200_ddc_algo_bit_data_post_xfer(struct i2c_adapter *adapter)
{
struct mgag200_ddc *ddc = i2c_get_adapdata(adapter);
struct mga_device *mdev = ddc->mdev;
mutex_unlock(&mdev->rmmio_lock);
}
static void mgag200_ddc_release(struct drm_device *dev, void *res)
{
struct mgag200_ddc *ddc = res;
@@ -133,6 +155,8 @@ struct i2c_adapter *mgag200_ddc_create(struct mga_device *mdev)
bit->setscl = mgag200_ddc_algo_bit_data_setscl;
bit->getsda = mgag200_ddc_algo_bit_data_getsda;
bit->getscl = mgag200_ddc_algo_bit_data_getscl;
bit->pre_xfer = mgag200_ddc_algo_bit_data_pre_xfer;
bit->post_xfer = mgag200_ddc_algo_bit_data_post_xfer;
bit->udelay = 10;
bit->timeout = usecs_to_jiffies(2200);

9
drivers/gpu/drm/mgag200/mgag200_mode.c
View File

@@ -743,23 +743,14 @@ void mgag200_crtc_atomic_destroy_state(struct drm_crtc *crtc, struct drm_crtc_st
int mgag200_vga_connector_helper_get_modes(struct drm_connector *connector)
{
struct mga_device *mdev = to_mga_device(connector->dev);
const struct drm_edid *drm_edid;
int count;
/*
* Protect access to I/O registers from concurrent modesetting
* by acquiring the I/O-register lock.
*/
mutex_lock(&mdev->rmmio_lock);
drm_edid = drm_edid_read(connector);
drm_edid_connector_update(connector, drm_edid);
count = drm_edid_connector_add_modes(connector);
drm_edid_free(drm_edid);
mutex_unlock(&mdev->rmmio_lock);
return count;
}