Consider moving the init of pl330 to earlier?

From: Ray Jui
Date: Thu Oct 09 2014 - 17:35:15 EST


How do you guys like the idea of moving the driver initialization of the pl330 DMA driver to earlier? For example, to arch_initcall_sync or subsys_initcall? Currently the pl330 driver is registered through module_amba_driver call, which translates to device_initcall in the end. This is a bit late considering in many systems, DMA controller is one of the core components that may have many slave devices depending on. Most slave drivers are typically done at device_initcall. When done at the same level, DMA may not be ready while the slave devices are being initialized. In addition, under the drivers/dma directory, we currently have various other DMA drivers also done at subsys_initcall.

One issue that I'm seeing with the Broadcom Cygnus SoC is that, when we try to use DMA with SPI (PL022), the request for DMA channel would fail because the spi-pl022 driver we use is initialized at subsys_initcall. At the time the PL330 driver is not yet initialized. The reason why spi-pl022 is done at subsys_initcall is that some regulators communicate through the SPI bus so people decided to move it to earlier (commit 25c8e03b by Linus Walleij), which seems to be a valid reason to me.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at