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From:   Javier Gonzalez <javier@cnexlabs.com>
To:     =?utf-8?B?TWF0aWFzIEJqw7hybGluZw==?= <mb@lightnvm.io>
CC:     "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [PATCH 08/20] lightnvm: complete geo structure with maxoc*
Thread-Topic: [PATCH 08/20] lightnvm: complete geo structure with maxoc*
Thread-Index: AQHTqvYt5cpllOgM1U67HfLhiBYBOqOwDE2AgAACtoCAAB7QAIAAAdgAgAACcoCAAAC7AA==
Date:   Thu, 22 Feb 2018 10:03:30 +0000
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Javier

> On 22 Feb 2018, at 11.00, Matias Bj=C3=B8rling <mb@lightnvm.io> wrote:
>=20
> On 02/22/2018 10:52 AM, Javier Gonzalez wrote:
>>> On 22 Feb 2018, at 10.45, Matias Bj=C3=B8rling <mb@lightnvm.io> =
wrote:
>>>=20
>>> On 02/22/2018 08:55 AM, Javier Gonzalez wrote:
>>>>> On 22 Feb 2018, at 08.45, Matias Bj=C3=B8rling <mb@lightnvm.io> =
wrote:
>>>>>=20
>>>>> On 02/21/2018 10:26 AM, Javier Gonz=C3=A1lez wrote:
>>>>>> Complete the generic geometry structure with the maxoc and =
maxocpu
>>>>>> felds, present in the 2.0 spec.
>>>>>> Signed-off-by: Javier Gonz=C3=A1lez <javier@cnexlabs.com>
>>>>>> ---
>>>>>>  drivers/nvme/host/lightnvm.c | 4 ++++
>>>>>>  include/linux/lightnvm.h     | 2 ++
>>>>>>  2 files changed, 6 insertions(+)
>>>>>> diff --git a/drivers/nvme/host/lightnvm.c =
b/drivers/nvme/host/lightnvm.c
>>>>>> index cca32da05316..9c1f8225c4e1 100644
>>>>>> --- a/drivers/nvme/host/lightnvm.c
>>>>>> +++ b/drivers/nvme/host/lightnvm.c
>>>>>> @@ -318,6 +318,8 @@ static int nvme_nvm_setup_12(struct =
nvme_nvm_id12 *id,
>>>>>>  	dev_geo->c.ws_min =3D sec_per_pg;
>>>>>>  	dev_geo->c.ws_opt =3D sec_per_pg;
>>>>>>  	dev_geo->c.mw_cunits =3D 8;		/* default to =
MLC safe values */
>>>>>> +	dev_geo->c.maxoc =3D dev_geo->all_luns;	/* default to 1 =
chunk per LUN */
>>>>>> +	dev_geo->c.maxocpu =3D 1;			/* =
default to 1 chunk per LUN */
>>>>>=20
>>>>> One can't assume that it is 1 open chunk per lun. If you need this =
for specific hardware, make a quirk for it.
>>>> Which default you want for 1.2 if not specified then? I use 1 =
because it
>>>> has been the implicit default until now.
>>>=20
>>> INT_MAX, since it then allows the maximum of open chunks. It cannot =
be assumed that other 1.2 devices is limited to a single open chunk.
>> So you want the default to be that all blocks on the device can be
>> opened at the same time. Interesting... I guess that such a SSD will
>> have a AA battery attached to it, but fine by me if that's how you =
want
>> it.
>=20
> I feel you're a bit sarcastic here. One may think of SLC and other =
memories that does one-shot programming. In that case no caching is =
needed, and therefore power-caps can be limited on the hardware.

Sure. Hope people move to 2.0 then for all >SLC memories out there,
otherwise we'll see a lot of quirks coming in. Thought we wanted to be
generic.

>=20
>> Assuming this, can we instead set it to the reported number of =
chunks,
>> since this is the hard limit anyway.
>=20
> Works for me.

Cool. I'll add this to the next version.

Javier

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