ST STM32L4+ Series Reference Manual page 937

RM0432
If the Tearing Effect Interrupt Enable (TEIE) bit of the DSI Wrapper Interrupt Enable Register
(DSI_WIER) is set, an interrupt is generated.
Tearing effect through DSI link
When the TESRC bit of the DSI Wrapper Configuration Register (DSI_WCFGR) is reset, the
Tearing effect is managed through the DSI link:
The DSI Host performs a double Bus-Turn-Around (BTA) after sending the set_tear_on
command granting the ownership of the link to the DSI display. The Display holds the
ownership of the bus until the tear event occurs, which is indicated to the DSI Host by a D-
PHY trigger event. The DSI Host then decodes the trigger and reports the event setting the
Tearing Effect Interrupt Flag (TEIF) bit of the DSI Wrapper Interrupt and Status Register
(DSI_WISR).
If the Tearing Effect Interrupt Enable (TEIE )bit of the DSI Wrapper Interrupt Enable Register
(DSI_WIER) is set, an interrupt is generated.
To use this function, it is necessary to issue a set_tear_on command after the update of the
display using the WMS and WMC DCS commands. This procedure halts the DSI link until
the display is ready to receive a new frame update.
The DSI Host does not automatically generate the tearing effect request (double BTA) after
a WMS/WMC sequence for flexibility purposes. This way several regions of the display can
be updated improving DSI bandwidth usage. Tearing effect request must always be
triggered by a set_tear_on command in the DSI Host implementation.
Configure the following registers to activate the tearing effect:
•
DSI Host Command mode Configuration Register (DSI_CMCR): TEARE;
•
DSI Host Protocol Configuration Register (DSI_PCR): BTAE.
DSI Host (DSIHOST) applied to STM32L4R9xx and STM32L4S9xx only
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