Re: [PATCH v2 01/22] block: add eMMC block device type

[Cédric Le Goater]

On 2/24/21 8:13 PM, Sai Pavan Boddu wrote:
> Hi Cedric,
> 
> 
>> -----Original Message-----
>> From: Cédric Le Goater <clg@kaod.org>
>> Sent: Wednesday, February 24, 2021 7:25 PM
>> To: Stefan Hajnoczi <stefanha@redhat.com>; Sai Pavan Boddu
>> <saipava@xilinx.com>
>> Cc: Philippe Mathieu-Daudé <philmd@redhat.com>; Markus Armbruster
>> <armbru@redhat.com>; Kevin Wolf <kwolf@redhat.com>; Max Reitz
>> <mreitz@redhat.com>; Vladimir Sementsov-Ogievskiy
>> <vsementsov@virtuozzo.com>; Eric Blake <eblake@redhat.com>; Joel Stanley
>> <joel@jms.id.au>; Vincent Palatin <vpalatin@chromium.org>; Dr. David Alan
>> Gilbert <dgilbert@redhat.com>; Thomas Huth <thuth@redhat.com>; Peter
>> Maydell <peter.maydell@linaro.org>; Alistair Francis
>> <alistair.francis@wdc.com>; Edgar Iglesias <edgari@xilinx.com>; Luc Michel
>> <luc.michel@greensocs.com>; Paolo Bonzini <pbonzini@redhat.com>; qemu-
>> devel@nongnu.org; qemu-block@nongnu.org
>> Subject: Re: [PATCH v2 01/22] block: add eMMC block device type
>>
>> On 2/24/21 12:40 PM, Stefan Hajnoczi wrote:
>>> On Tue, Feb 23, 2021 at 05:35:20PM +0000, Sai Pavan Boddu wrote:
>>>> Hi Philippe,
>>>>
>>>>> -----Original Message-----
>>>>> From: Philippe Mathieu-Daudé <philmd@redhat.com>
>>>>> Sent: Monday, February 22, 2021 5:34 PM
>>>>> To: Sai Pavan Boddu <saipava@xilinx.com>; Markus Armbruster
>>>>> <armbru@redhat.com>; Kevin Wolf <kwolf@redhat.com>; Max Reitz
>>>>> <mreitz@redhat.com>; Vladimir Sementsov-Ogievskiy
>>>>> <vsementsov@virtuozzo.com>; Eric Blake <eblake@redhat.com>; Joel
>>>>> Stanley <joel@jms.id.au>; Cédric Le Goater <clg@kaod.org>; Vincent
>>>>> Palatin <vpalatin@chromium.org>; Dr. David Alan Gilbert
>>>>> <dgilbert@redhat.com>; Thomas Huth <thuth@redhat.com>; Stefan
>>>>> Hajnoczi <stefanha@redhat.com>; Peter Maydell
>>>>> <peter.maydell@linaro.org>; Alistair Francis
>>>>> <alistair.francis@wdc.com>; Edgar Iglesias <edgari@xilinx.com>; Luc
>>>>> Michel <luc.michel@greensocs.com>; Paolo Bonzini
>>>>> <pbonzini@redhat.com>
>>>>> Cc: Sai Pavan Boddu <saipava@xilinx.com>; qemu-devel@nongnu.org;
>>>>> qemu- block@nongnu.org
>>>>> Subject: Re: [PATCH v2 01/22] block: add eMMC block device type
>>>>>
>>>>> On 2/22/21 9:20 AM, Sai Pavan Boddu wrote:
>>>>>> From: Vincent Palatin <vpalatin@chromium.org>
>>>>>>
>>>>>> Add new block device type.
>>>>>>
>>>>>> Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
>>>>>> [SPB: Rebased over 5.1 version]
>>>>>> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
>>>>>> Signed-off-by: Joel Stanley <joel@jms.id.au>
>>>>>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>>>>>> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
>>>>>> ---
>>>>>>  include/sysemu/blockdev.h | 1 +
>>>>>>  blockdev.c                | 1 +
>>>>>>  2 files changed, 2 insertions(+)
>>>>>>
>>>>>> diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
>>>>>> index 3b5fcda..eefae9f 100644
>>>>>> --- a/include/sysemu/blockdev.h
>>>>>> +++ b/include/sysemu/blockdev.h
>>>>>> @@ -24,6 +24,7 @@ typedef enum {
>>>>>>       */
>>>>>>      IF_NONE = 0,
>>>>>>      IF_IDE, IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD,
>>>>>> IF_VIRTIO, IF_XEN,
>>>>>> +    IF_EMMC,
>>>>>>      IF_COUNT
>>>>>>  } BlockInterfaceType;
>>>>>>
>>>>>> diff --git a/blockdev.c b/blockdev.c index cd438e6..390d43c 100644
>>>>>> --- a/blockdev.c
>>>>>> +++ b/blockdev.c
>>>>>> @@ -83,6 +83,7 @@ static const char *const if_name[IF_COUNT] = {
>>>>>>      [IF_SD] = "sd",
>>>>>>      [IF_VIRTIO] = "virtio",
>>>>>>      [IF_XEN] = "xen",
>>>>>> +    [IF_EMMC] = "emmc",
>>>>>>  };
>>>>>
>>>>> We don't need to introduce support for the legacy -drive magic.
>>>>>
>>>>> -device should be enough for this device, right?
>>>> [Sai Pavan Boddu] I was seeing to use -device for emmc. But I see we
>> anyway need blockdev support for this, which would require us the use -drive.
>>>>
>>>> Can you give some pointers, how to approach this ?
>>>
>>> It is probably not necessary to add a new IF_ constant. Would this work:
>>>
>>>   -drive if=none,id=emmc0,file=test.img,format=raw
>>>   -device emmc,...,drive=emmc0
>>>
>>> Or the more modern:
>>>
>>>   -blockdev node-name=emmc0,driver=file,filename=test.img
>>>   -device emmc,...,drive=emmc0
>>>
>>> ?
>>>
>>> (The syntax might need small tweaks but is shows the general idea.)
>>
>> Yes. This is better.
>>
>> We could have an "emmc" device inheriting from "sd-card". The "emmc"
>> property would not be necessary anymore and may be, we could cleanup up
>> some parts doing :
>>
>>     if (sd->emmc) { /* eMMC */
>>         ...
>>     } else {
>>
>>     }
>>
>> with SDCardClass handlers. the SWITCH_FUNCTION command is a good
>> candidate, CMD8 also.
> [Sai Pavan Boddu] Nice, this approach looks clean.
> But we still may be depending on emmc property. Not sure!

It could be a SDCardClass attribute instead since it's a constant for
the emmc device.

C. 

> 
> I would get back with v3, your review on those patches would be great.
> 
> Thanks & Regards,
> Sai Pavan
>>
>> C.