Re: [PATCH] ARM: dts: gta04: fix excess dma channel usage

Tony Lindgren
2023-03-27T08:13:43Z

* Andreas Kemnade <andreas@kemnade.info> [230113 23:12]:
> From: "H. Nikolaus Schaller" <hns@goldelico.com>
>
> OMAP processors support 32 channels but there is no check or
> inspect this except booting a device and looking at dmesg reports
> of not available channels.
>
> Recently some more subsystems with DMA (aes1+2) were added filling
> the list of dma channels beyond the limit of 32 (even if other
> parameters indicate 96 or 128 channels). This leads to random
> subsystem failures i(e.g. mcbsp for audio) after boot or boot
> messages that DMA can not be initialized.
>
> Another symptom is that
>
> /sys/kernel/debug/dmaengine/summary
>
> has 32 entries and does not show all required channels.
>
> Fix by disabling unused (on the GTA04 hardware) mcspi1...4.
> Each SPI channel allocates 4 DMA channels rapidly filling
> the available ones.
>
> Disabling unused SPI modules on the OMAP3 SoC may also save
> some energy (has not been checked).

Applying this into omap-for-v6.4/dt based on what we discussed
in this thread earlier.

Thanks,

Tony