Re: [PATCH v2 2/5] m68k - set up platform device for mvme147_scsi

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Arnd,

Am 12.07.2022 um 21:07 schrieb Michael Schmitz:
> Hi Arnd,
>
> Am 12.07.2022 um 20:12 schrieb Arnd Bergmann:
>> On Tue, Jul 12, 2022 at 9:58 AM Michael Schmitz <schmitzmic@gmail.com>
>> wrote:
>>> +
>>> +static const struct resource mvme147_scsi_rsrc[] __initconst = {
>>> +       DEFINE_RES_MEM(MVME147_SCSI_BASE, 0xff),
>>
>> Still the wrong size?
>
> Too true - forgot to fix that, sorry.
>
>>
>>> +       DEFINE_RES_IRQ(MVME147_IRQ_SCSI_PORT),
>>> +};
>>> +
>>> +int __init mvme147_platform_init(void)
>>> +{
>>> +       struct platform_device *pdev;
>>> +       int rv = 0;
>>> +
>>> +       pdev = platform_device_register_simple("mvme147-scsi", -1,
>>> +               mvme147_scsi_rsrc, ARRAY_SIZE(mvme147_scsi_rsrc));
>>
>> I think you actually have to use platform_device_register_full() to pass
>> a DMA mask here: As I understand it, the dma_set_mask_and_coherent()
>> call in the driver fails if the device is not already marked as dma
>> capable by having an initial mask set.
>
> I'll take a look at that - if true, this requires the amiga-a3000-scsi
> platform device set-up be changed in the same way (the gvp11 and a2091
> drivers inherit the DMA mask from the Zorro bus default, so ought to
> work OK).

I think we are good with using platform_device_register_simple():

setup_pdev_dma_masks() sets the DMA mask to 32 bit when allocating a new 
platform device, and platform_device_register_full() only changes that 
when passed in a non-zero mask in pdevinfo.

platform_device_register_simple() leaves the pdevinfo mask zero, so the 
32 bit default set in setup_pdev_dma_masks() survives.

Cheers,

	Michael

>
> Cheers,
>
>     Michael
>
>> The way this normally works is that the device gets created with a mask
>> that reflects the capabilities of the bus, while the driver sets a mask
>> based on what it wants to program into the device, and the dma-mapping
>> interfaces ensure that we only use the intersection of those.
>>
>>         Arnd
>>