Re: [dpdk-dev] [PATCH] eventdev: negate maintenance capability flag

["Van Haaren, Harry" <harry.van.haaren@intel.com>]

> -----Original Message-----
> From: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
> Sent: Wednesday, November 10, 2021 9:29 AM
> To: jerinj@marvell.com; Jerin Jacob <jerinjacobk@gmail.com>; Sunil Kumar Kori
> <skori@marvell.com>
> Cc: dev@dpdk.org; Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>;
> Hemant Agrawal <hemant.agrawal@nxp.com>; Nipun Gupta
> <nipun.gupta@nxp.com>; Van Haaren, Harry <harry.van.haaren@intel.com>;
> Thomas Monjalon <thomas@monjalon.net>; David Marchand
> <david.marchand@redhat.com>; Gujjar, Abhinandan S
> <abhinandan.gujjar@intel.com>; Carrillo, Erik G <erik.g.carrillo@intel.com>;
> Jayatheerthan, Jay <jay.jayatheerthan@intel.com>; Yigit, Ferruh
> <ferruh.yigit@intel.com>; Akhil Goyal <gakhil@marvell.com>; mattias.ronnblom
> <mattias.ronnblom@ericsson.com>
> Subject: [PATCH] eventdev: negate maintenance capability flag
> 
> Replace RTE_EVENT_DEV_CAP_REQUIRES_MAINT, which signaled the need
> for the application to call rte_event_maintain(), with
> RTE_EVENT_DEV_CAP_MAINTENANCE_FREE, which does the opposite (i.e.,
> signifies that the event device does not require maintenance).
> 
> This approach is more in line with how other eventdev hardware and/or
> software limitations are handled in the Eventdev API.
> 
> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>

Generally patch looks fine to me, but on testing I got a strange warning from the
compiler on the OPDL driver:

In file included from ../drivers/event/opdl/opdl_evdev.h:8,
                 from ../drivers/event/opdl/opdl_evdev.c:15:
../drivers/event/opdl/opdl_evdev.c: In function ‘opdl_info_get’:
../lib/eventdev/rte_eventdev.h:302:44: warning: conversion from ‘long long unsigned int’ to ‘un
signed char’ changes value from ‘1024’ to ‘0’ [-Woverflow]
  302 | #define RTE_EVENT_DEV_CAP_MAINTENANCE_FREE (1ULL << 10)
      |                                            ^
../drivers/event/opdl/opdl_evdev.c:379:34: note: in expansion of macro ‘RTE_EVENT_DEV_CAP_MAINT
ENANCE_FREE’
  379 |                                  RTE_EVENT_DEV_CAP_MAINTENANCE_FREE,
      |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Investigating, RTE_EVENT_DEV_CAP_* are assigned to struct rte_event_dev_info::event_dev_cap,
which is a uint32_t. The error suggests that the variable being assigned to is a "unsigned char"? 

<snip>

>  static void
> diff --git a/drivers/event/opdl/opdl_evdev.c b/drivers/event/opdl/opdl_evdev.c
> index 5007e9a7bf..787ee4713d 100644
> --- a/drivers/event/opdl/opdl_evdev.c
> +++ b/drivers/event/opdl/opdl_evdev.c
> @@ -376,6 +376,7 @@ opdl_info_get(struct rte_eventdev *dev, struct
> rte_event_dev_info *info)
>  		.max_num_events = OPDL_INFLIGHT_EVENTS_TOTAL,
>  		.event_dev_cap = RTE_EVENT_DEV_CAP_BURST_MODE |
>  				 RTE_EVENT_DEV_CAP_CARRY_FLOW_ID,
> +				 RTE_EVENT_DEV_CAP_MAINTENANCE_FREE,
>  	};

Aha! Replace:
>  				 RTE_EVENT_DEV_CAP_CARRY_FLOW_ID,
with:
>  				 RTE_EVENT_DEV_CAP_CARRY_FLOW_ID | 

The "," character was causing the _FREE flag to not be combined with the previous
flags field, instead being its own (unnamed?) assignment to the struct rte_event_dev_info.

With that , to | change, all looks good to me. -Harry