查看“DSI internal peripheral”的源代码

==Article purpose==
The purpose of this article is to:
* Introduce the DSI peripheral and its main features,
* Indicate the level of security supported by this hardware block,
* Explain how each instance can be allocated to the three runtime contexts and linked to the corresponding software components,
* Explain, where necessary, how to configure the DSI peripheral.

==Peripheral overview==
The DSI peripheral implements all the protocol functions defined in the MIPI<sup>&reg;</sup> Display Serial Interface (MIPI<sup>&reg;</sup> DSI) specification. It provides an interface to communicate with a DSI-compliant display. The MIPI<sup>&reg;</sup> DSI is part of a group of communication protocols defined by the MIPI<sup>&reg;</sup> Alliance <ref>https://www.mipi.org MIPI<sup>&reg;</sup> Alliance</ref>. 

===Features===
Refer to the [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the complete list of features, and to the software components, introduced below, to see which features are implemented.

===Security support===
The DSI is a '''non-secure''' peripheral.

==Peripheral usage and associated software==
Even if some MIPI DSI modes are supported by the DSI internal peripheral, in practice:
* software frameworks like U-Boot or Linux<sup>&reg;</sup> kernel do not support all the possible modes.
* hardware integration constraints such as support for all the clock values or the pll configurations make it difficult to use all possible modes.


Select a MIPI DSI panel or bridge supporting the '''DSI video burst mode''' <ref name="AN4860"/> because this mode is supported by all software frameworks and is easier to fine tune. Please consider the following recommendations when selecting a MIPI DSI panel or bridge for your project:
* '''Pixel data transmission'''
** in DSI command mode: not supported by neither U-Boot nor Linux<sup>&reg;</sup> kernel, use instead the DSI video burst mode.
** in DSI video mode:
*** burst mode: supported
*** non-burst mode with sync events or pulses: supported with clock constraints to be considered <ref name="AN4860"/>.

* '''Command transmission''' (initialization sequence, backlight...)
** in DSI command mode: supported
** in DSI video mode:
***burst mode: supported if there is enough time to send commands before or/and after pixel data <ref name="AN4860"/>.
***non-burst mode with sync events or pulses: supported but there are timing constraints to be considered <ref name="AN4860"/>.

===Boot time===
The DSI is used at boot time for displaying a splash screen through the U-Boot framework <ref>[[U-Boot overview | U-Boot framework]]</ref>.

===Runtime===

====Overview====
The DSI internal peripheral runs on the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 non-secure core to be controlled by the Linux<sup>&reg;</sup>[[DRM KMS overview | DRM/KMS framework]].

Chapter [[#Peripheral assignment|Peripheral assignment]] describes which peripheral instance can be assigned to which context.

====Software frameworks====
{{:Internal_peripherals_software_table_template}}
 | Visual
 | [[DSI internal peripheral|DSI]]
 | 
 | [[DRM KMS overview | DRM/KMS framework]]
 | 
 |
 |-
 |}

====Peripheral configuration====
The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the [[STM32CubeMX]] tool for all internal peripherals, and then manually completed (particularly for external peripherals), according to the information given in the corresponding software framework article or for Linux<sup>&reg;</sup> in the [[DSI device tree configuration]] article.

====Peripheral assignment====
{{:Internal_peripherals_assignment_table_template}}
<onlyinclude>
 | rowspan="1" | Visual
 | rowspan="1" | [[DSI internal peripheral|DSI]]
 | DSI
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 |
 |
 |-
</onlyinclude>
 |}

==How to go further==
Refer to the STM32 DSI application note (AN4860) <ref name="AN4860">[[STM32MP15 resources#AN4860 | DSI host on STM32 MCUs Application Note (AN4860)]]</ref> for a detailed description of the DSI peripheral and applicable use-cases.

Even if this application note is related to STM32 microcontrollers, it also applies to STM32 MPUs.

==References==
<references/>