Re: [Qemu-devel] [PATCH 1/3] pflash_cfi01: add pflash_cfi01_init

[Peter Crosthwaite]

On Sun, Sep 27, 2015 at 10:51 AM, Max Filippov <address@hidden> wrote:
> On Sun, Sep 27, 2015 at 8:25 PM, Peter Crosthwaite
> <address@hidden> wrote:
>> On Sun, Sep 27, 2015 at 10:16 AM, Max Filippov <address@hidden> wrote:
>>> pflash_cfi01_register always registers FLASH to the default
>>> system_memory region, which may not always be the right thing.
>>>
>>> Provide pflash_cfi01_init function that only creates FLASH device and
>>> sets its properties, leaving MMIO region registration to its caller.
>>>
>>
>> You should just use QOM to create your device inline without need for
>> a construction helper. See Vexpress's ve_pflash_cfi01_register for an
>> example.
>
> I thought about it and it looks like a lot of boilerplate code for nothing.

Not really. It self documents the code. This is instantly understandable:

    qdev_prop_set_uint32(dev, "num-blocks",
                         VEXPRESS_FLASH_SIZE / VEXPRESS_FLASH_SECT_SIZE);
    qdev_prop_set_uint64(dev, "sector-length", VEXPRESS_FLASH_SECT_SIZE);
    qdev_prop_set_uint8(dev, "width", 4);
    qdev_prop_set_uint8(dev, "device-width", 2);
    qdev_prop_set_bit(dev, "big-endian", false);
    qdev_prop_set_uint16(dev, "id0", 0x89);
    qdev_prop_set_uint16(dev, "id1", 0x18);
    qdev_prop_set_uint16(dev, "id2", 0x00);
    qdev_prop_set_uint16(dev, "id3", 0x00);
    qdev_prop_set_string(dev, "name", name);

Whereas a call to pflash_cfi_register is a jumble of numbers without
any labelling of what is what. In this scheme you don't have to open
headers to figure out what args are.

> Maybe it'd be better to remove qdev_init_nofail call from that init function
> and let ve_pflash_cfi01_register reuse it too?
>

There was a conscious decision some time ago to get rid of qdev init
helper functions as provided by devs themselves. The interface between
dev and board should be QOM.

Regards,
Peter

> --
> Thanks.
> -- Max