On 5/14/2020 9:56 AM, Greg KH wrote:
On Thu, May 14, 2020 at 09:05:30AM -0600, Jeffrey Hugo wrote:
Wow, thank you for the near immediate response. I'm am quite impressed.
On 5/14/2020 8:12 AM, Greg KH wrote:
On Thu, May 14, 2020 at 08:07:41AM -0600, Jeffrey Hugo wrote:
/* Copyright (c) 2019-2020, The Linux Foundation. All rights reserved. */
+#include <linux/cdev.h>
+#include <linux/idr.h>
+#include <linux/list.h>
+#include <linux/kref.h>
+#include <linux/mhi.h>
#include <linux/module.h>
#include <linux/msi.h>
+#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
@@ -13,9 +19,242 @@
#define PCI_DEV_AIC100 0xa100
#define QAIC_NAME "Qualcomm Cloud AI 100"
+#define QAIC_MAX_MINORS 256
Why have a max?
Why not just use a misc device so you make the logic a lot simple, no
class or chardev logic to mess with at all.
It was our understanding that the preference is not to add new misc devices.
Huh, who said that? Not the char/misc maintainer (i.e. me) :)
As I go and try to find a supporting reference for that, I cannot find one,
so I'm not entirely sure where that idea came from.
In addition, we see that the Habana Labs driver also uses chardev, and has
chosen the same max. We assumed that since their driver is already
accepted, using the same mechanisms where applicable would be the preferred
approach.
They had good reasons why not to use a chardev and convinced me of it.
If you can't come up with them, then stick with a misc for now please.
Interesting. I didn't see any discussion on this.
Specific to the max, 256 was chosen as being a factor larger than the
largest system we have, therefore we figured it wouldn't be hit for a long
while even as we try to have a look at what might happen down the road.
Looking at the Habana code, it looks like they have the same value for much
of the same reasons, although their usecases may vary from ours somewhat.
Max numbers for no good reason are not a good thing to have.
At this time, I don't think we have a strong requirement for a chardev, so
we could investigate a switch over to a misc dev if you would prefer that
over following the Habana Labs precedent. All I ask is a confirmation that
is the approach you would like to see going forward after reviewing the
above.
Please use misc.
Ok, will investigate.
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
