Re: [PATCH 08/20] lightnvm: complete geo structure with maxoc*

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On 02/22/2018 10:52 AM, Javier Gonzalez wrote:
On 22 Feb 2018, at 10.45, Matias Bjørling <mb@xxxxxxxxxxx> wrote:

On 02/22/2018 08:55 AM, Javier Gonzalez wrote:
On 22 Feb 2018, at 08.45, Matias Bjørling <mb@xxxxxxxxxxx> wrote:

On 02/21/2018 10:26 AM, Javier González wrote:
Complete the generic geometry structure with the maxoc and maxocpu
felds, present in the 2.0 spec.
Signed-off-by: Javier González <javier@xxxxxxxxxxxx>
---
  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 = sec_per_pg;
  	dev_geo->c.ws_opt = sec_per_pg;
  	dev_geo->c.mw_cunits = 8;		/* default to MLC safe values */
+	dev_geo->c.maxoc = dev_geo->all_luns;	/* default to 1 chunk per LUN */
+	dev_geo->c.maxocpu = 1;			/* default to 1 chunk per LUN */

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.

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.

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.


Assuming this, can we instead set it to the reported number of chunks,
since this is the hard limit anyway.


Works for me.



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