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drm/mali-dp: Improve writeback handling for DP500.

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Mali DP500 operates in continuous writeback mode (writes frame content
until stopped) and it needs special handling in order to behave like
a one-shot writeback engine. The original state machine added for DP500
was a bit fragile, as it did not handle correctly cases where a new
atomic commit was in progress when the SE IRQ happens and it would
commit some partial updates.

Improve the handling by adding a parameter to the set_config_valid()
function to clear the config valid bit in hardware before starting a
new commit and by introducing a MW_RESTART state in the writeback
state machine to cater for the case where a new writeback commit
gets submitted while the last one is still being active.

Reported-by: Brian Starkey <brian.starkey@arm.com>
Reviewed-by: Brian Starkey <brian.starkey@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
This commit is contained in:
Liviu Dudau 2018-06-15 16:56:09 +01:00
parent 8cbc5caf36
commit 0735cfdf0a
3 changed files with 36 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
drivers/gpu/drm/arm/malidp_drv.c
View file

@ -171,7 +171,7 @@ static int malidp_set_and_wait_config_valid(struct drm_device *drm)
struct malidp_hw_device *hwdev = malidp->dev;
int ret;
hwdev->hw->set_config_valid(hwdev);
hwdev->hw->set_config_valid(hwdev, 1);
/* don't wait for config_valid flag if we are in config mode */
if (hwdev->hw->in_config_mode(hwdev)) {
atomic_set(&malidp->config_valid, MALIDP_CONFIG_VALID_DONE);
@ -230,6 +230,7 @@ static void malidp_atomic_commit_tail(struct drm_atomic_state *state)
* know that we are updating registers
*/
atomic_set(&malidp->config_valid, MALIDP_CONFIG_START);
malidp->dev->hw->set_config_valid(malidp->dev, 0);
drm_atomic_helper_commit_modeset_disables(drm, state);

39
drivers/gpu/drm/arm/malidp_hw.c
View file

@ -27,7 +27,8 @@ enum {
MW_NOT_ENABLED = 0, /* SE writeback not enabled */
MW_ONESHOT, /* SE in one-shot mode for writeback */
MW_START, /* SE started writeback */
MW_STOP, /* SE finished writeback */
MW_RESTART, /* SE will start another writeback after this one */
MW_STOP, /* SE needs to stop after this writeback */
};
static const struct malidp_format_id malidp500_de_formats[] = {
@ -231,9 +232,12 @@ static bool malidp500_in_config_mode(struct malidp_hw_device *hwdev)
return false;
}
static void malidp500_set_config_valid(struct malidp_hw_device *hwdev)
static void malidp500_set_config_valid(struct malidp_hw_device *hwdev, u8 value)
{
malidp_hw_setbits(hwdev, MALIDP_CFG_VALID, MALIDP500_CONFIG_VALID);
if (value)
malidp_hw_setbits(hwdev, MALIDP_CFG_VALID, MALIDP500_CONFIG_VALID);
else
malidp_hw_clearbits(hwdev, MALIDP_CFG_VALID, MALIDP500_CONFIG_VALID);
}
static void malidp500_modeset(struct malidp_hw_device *hwdev, struct videomode *mode)
@ -386,7 +390,11 @@ static int malidp500_enable_memwrite(struct malidp_hw_device *hwdev,
/* enable the scaling engine block */
malidp_hw_setbits(hwdev, MALIDP_SCALE_ENGINE_EN, de_base + MALIDP_DE_DISPLAY_FUNC);
hwdev->mw_state = MW_START;
/* restart the writeback if already enabled */
if (hwdev->mw_state != MW_NOT_ENABLED)
hwdev->mw_state = MW_RESTART;
else
hwdev->mw_state = MW_START;
malidp_hw_write(hwdev, fmt_id, base + MALIDP_MW_FORMAT);
switch (num_planes) {
@ -415,7 +423,7 @@ static void malidp500_disable_memwrite(struct malidp_hw_device *hwdev)
{
u32 base = malidp_get_block_base(hwdev, MALIDP_DE_BLOCK);
if (hwdev->mw_state == MW_START)
if (hwdev->mw_state == MW_START || hwdev->mw_state == MW_RESTART)
hwdev->mw_state = MW_STOP;
malidp_hw_clearbits(hwdev, MALIDP_SE_MEMWRITE_EN, MALIDP500_SE_CONTROL);
malidp_hw_clearbits(hwdev, MALIDP_SCALE_ENGINE_EN, base + MALIDP_DE_DISPLAY_FUNC);
@ -500,9 +508,12 @@ static bool malidp550_in_config_mode(struct malidp_hw_device *hwdev)
return false;
}
static void malidp550_set_config_valid(struct malidp_hw_device *hwdev)
static void malidp550_set_config_valid(struct malidp_hw_device *hwdev, u8 value)
{
malidp_hw_setbits(hwdev, MALIDP_CFG_VALID, MALIDP550_CONFIG_VALID);
if (value)
malidp_hw_setbits(hwdev, MALIDP_CFG_VALID, MALIDP550_CONFIG_VALID);
else
malidp_hw_clearbits(hwdev, MALIDP_CFG_VALID, MALIDP550_CONFIG_VALID);
}
static void malidp550_modeset(struct malidp_hw_device *hwdev, struct videomode *mode)
@ -1005,15 +1016,21 @@ static irqreturn_t malidp_se_irq(int irq, void *arg)
/* disable writeback after stop */
hwdev->mw_state = MW_NOT_ENABLED;
break;
case MW_RESTART:
drm_writeback_signal_completion(&malidp->mw_connector, 0);
/* fall through to a new start */
case MW_START:
/* writeback started, need to emulate one-shot mode */
hw->disable_memwrite(hwdev);
/*
* only set config_valid HW bit if there is no
* other update in progress
* only set config_valid HW bit if there is no other update
* in progress or if we raced ahead of the DE IRQ handler
* and config_valid flag will not be update until later
*/
if (atomic_read(&malidp->config_valid) != MALIDP_CONFIG_START)
hw->set_config_valid(hwdev);
status = malidp_hw_read(hwdev, hw->map.dc_base + MALIDP_REG_STATUS);
if ((atomic_read(&malidp->config_valid) != MALIDP_CONFIG_START) ||
(status & hw->map.dc_irq_map.vsync_irq))
hw->set_config_valid(hwdev, 1);
break;
}
}

11
drivers/gpu/drm/arm/malidp_hw.h
View file

@ -152,12 +152,13 @@ struct malidp_hw {
bool (*in_config_mode)(struct malidp_hw_device *hwdev);
/*
* Set configuration valid flag for hardware parameters that can
* be changed outside the configuration mode. Hardware will use
* the new settings when config valid is set after the end of the
* current buffer scanout
* Set/clear configuration valid flag for hardware parameters that can
* be changed outside the configuration mode to the given value.
* Hardware will use the new settings when config valid is set,
* after the end of the current buffer scanout, and will ignore
* any new values for those parameters if config valid flag is cleared
*/
void (*set_config_valid)(struct malidp_hw_device *hwdev);
void (*set_config_valid)(struct malidp_hw_device *hwdev, u8 value);
/*
* Set a new mode in hardware. Requires the hardware to be in