Re: [PATCH v2] dmaengine: dw: Select only supported masters for ACPI devices

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Thu, Sep 19, 2024 at 09:51:48PM +0300, Serge Semin wrote:
> The recently submitted fix-commit revealed a problem in the iDMA32
> platform code. Even though the controller supported only a single master
> the dw_dma_acpi_filter() method hard-coded two master interfaces with IDs
> 0 and 1. As a result the sanity check implemented in the commit
> b336268dde75 ("dmaengine: dw: Add peripheral bus width verification") got
> incorrect interface data width and thus prevented the client drivers
> from configuring the DMA-channel with the EINVAL error returned. E.g. the
> next error was printed for the PXA2xx SPI controller driver trying to
> configure the requested channels:
> 
> > [  164.525604] pxa2xx_spi_pci 0000:00:07.1: DMA slave config failed
> > [  164.536105] pxa2xx_spi_pci 0000:00:07.1: failed to get DMA TX descriptor
> > [  164.543213] spidev spi-SPT0001:00: SPI transfer failed: -16
> 
> The problem would have been spotted much earlier if the iDMA32 controller
> supported more than one master interfaces. But since it supports just a
> single master and the iDMA32-specific code just ignores the master IDs in
> the CTLLO preparation method, the issue has been gone unnoticed so far.
> 
> Fix the problem by specifying a single master ID for both memory and
> peripheral devices on the ACPI-based platforms if there is only one master
> available on the controller. Thus the issue noticed for the iDMA32
> controllers will be eliminated and the ACPI-probed DW DMA controllers will
> be configured with the correct master ID by default.

Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Seems this fixes the bug I have seen.
Ferry, can you confirm?

-- 
With Best Regards,
Andy Shevchenko