Re: [PATCH] dmaengine: Consistently define pci_device_ids using named initializers

[Uwe Kleine-König (The Capable Hub)]

On Mon, May 04, 2026 at 01:29:12PM +0300, Andy Shevchenko wrote:
> On Mon, May 04, 2026 at 12:20:06PM +0200, Uwe Kleine-König (The Capable Hub) wrote:
> > The .driver_data member of the various struct pci_device_id arrays were
> > initialized by list expressions. This isn't easily readable if you're
> > not into PCI. Using named initializers is more explicit and thus easier
> > to parse. Also skip explicit assignments of 0 (which the compiler then
> > takes care of).
> > 
> > This change doesn't introduce changes to the compiled pci_device_id
> > arrays. Tested on x86 and arm64.
> 
> HSU driver has different change ("Also" is a strong sign to the split required).

HSU is in the category "skip explicit assignments of 0", so I think
that's fine. I could be talked into splitting if that's what is wanted.
 
> ...
> 
> >  static const struct pci_device_id pch_dma_id_table[] = {
> > -	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_8CH), 8 },
> > -	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_4CH), 4 },
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA1_8CH), 8}, /* UART Video */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA2_8CH), 8}, /* PCMIF SPI */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA3_4CH), 4}, /* FPGA */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA4_12CH), 12}, /* I2S */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA1_4CH), 4}, /* UART */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA2_4CH), 4}, /* Video SPI */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA3_4CH), 4}, /* Security */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA4_4CH), 4}, /* FPGA */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_DMA1_8CH), 8}, /* UART */
> > -	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_DMA2_4CH), 4}, /* SPI */
> > -	{ 0, },
> > +	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_8CH), .driver_data = 8 },
> > +	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_4CH), .driver_data = 4 },
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA1_8CH), .driver_data = 8 },		/* UART Video */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA2_8CH), .driver_data = 8 },		/* PCMIF SPI */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA3_4CH), .driver_data = 4 },		/* FPGA */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_DMA4_12CH), .driver_data = 12 },	/* I2S */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA1_4CH), .driver_data = 4 },		/* UART */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA2_4CH), .driver_data = 4 },		/* Video SPI */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA3_4CH), .driver_data = 4 },		/* Security */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_DMA4_4CH), .driver_data = 4 },		/* FPGA */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_DMA1_8CH), .driver_data = 8 },		/* UART */
> > +	{ PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_DMA2_4CH), .driver_data = 4 },		/* SPI */
> > +	{ },
> >  };
> 
> Use PCI_DEVICE_DATA() instead. Same may apply to DesignWare, but one needs to
> define the device IDs. I think I may help with that.

I'm not a fan of PCI_DEVICE_DATA. While it could indeed be used to
shorten the assignments here, it's less readable in my opinion.

Compare

	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_4CH), .driver_data = 4 },

with

	{ PCI_DEVICE_DATA(INTEL, PCI_DEVICE_ID_EG20T_PCH_DMA_4CH, 4) },

. For someone who doesn't know what PCI_DEVICE_DATA does, the latter is
less understandable.

Also PCI_DEVICE_DATA has a cast which is something I want to get rid of.

Best regards
Uwe

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