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iflib: leave only 1 receive descriptor unused

The pidx argument of isc_rxd_flush() indicates which is the last valid
receive descriptor to be used by the NIC. However, current code has
multiple issues:
  - Intel drivers write pidx to their RDT register, which means that
    NICs will only use the descriptors up to pidx-1 (modulo ring size N),
    and won't actually use the one pointed by pidx. This does not break
    reception, but it is anyway confusing and suboptimal (the NIC will
    actually see only N-2 descriptors as available, rather than N-1).
    Other drivers (if_vmx, if_bnxt, if_mgb) adhere to this semantic).
  - The semantic used by Intel (RDT is one descriptor past the last
     valid one) is used by most (if not all) NICs, and it is also used
     on the TX side (also in iflib). Since iflib is not currently
     using this semantic for RX, it must decrement fl->ifl_pidx
     (modulo N) before calling isc_rxd_flush(), and then the
     per-driver callback implementation must increment the index
     again (to match the real semantic). This is confusing and suboptimal.
  -  The iflib refill function is also called at initialization.
     However, in case the ring size is smaller than 128 (e.g. if_mgb),
     the refill function will actually prepare all the receive
     descriptors (N), without leaving one unused, as most of NICs assume
     (e.g. to avoid RDT to overrun RDH). I can speculate that the code
     looks like this right now because this issue showed up during
     testing (e.g. with if_mgb), and it was easy to workaround by
     decrementing pidx before isc_rxd_flush().

The goal of this change is to simplify the code (removing a bunch
of instructions from the RX fast path), and to make the semantic of
isc_rxd_flush() consistent across drivers. To achieve this, we:
  - change the semantics of the pidx argument to the usual one (that
    is the index one past the last valid one), so that both iflib and
    drivers avoid the decrement/increment dance.
  - fix the initialization code to prepare at most N-1 descriptors.

Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D26191

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Mark Johnston [Tue, 1 Sep 2020 20:13:50 +0000 (20:13 +0000)]

qlxgb: Initialize if_mtu before setting max_frame_size.

Previously we were relying on ether_ifattach() to set if_mtu, but
max_frame_size is initialized earlier. This fixes a regression
introduced by r250375.

PR: 249050
Submitted by: Christian Vallières <novacrash_@hotmail.com>
MFC after: 3 days

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Ian Lepore [Tue, 1 Sep 2020 19:06:08 +0000 (19:06 +0000)]

Document the fact that you must set an i2c slave address as well as the
upstream iicbus to configure this device using hints.

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Ryan Moeller [Tue, 1 Sep 2020 19:02:07 +0000 (19:02 +0000)]

Ensure zstreamdump subdir can be visited

Reported by: Thomas Laus
Sponsored by: iXsystems, Inc.

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Chuck Silvers [Tue, 1 Sep 2020 18:50:26 +0000 (18:50 +0000)]

Move all of the error prints in readsb() from stderr to stdout.
The only output from fsck that should go to stderr is the usage message.
if setup() fails then exit with EEXIT rather than 0.

Reviewed by: mckusick
Sponsored by: Netflix

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John Baldwin [Tue, 1 Sep 2020 16:20:42 +0000 (16:20 +0000)]

Fix a buffer overrun.

getln() returns 'len' valid characters. line[len] is out of bounds.

Reported by: CHERI
Reviewed by: brooks
Obtained from: CheriBSD
MFC after: 2 weeks
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D26197

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Marcin Wojtas [Tue, 1 Sep 2020 16:17:21 +0000 (16:17 +0000)]

Introduce the SDHCI driver for NXP QorIQ Layerscape SoCs

Implement support for an eSDHC controller found in NXP QorIQ Layerscape SoCs.

This driver has been tested with NXP LS1046A and LX2160A (Honeycomb board),
which is incompatible with the existing sdhci_fsl driver (aiming at older
chips from this family). As such, it is not intended as replacement for
the old driver, but rather serves as an improved alternative for SoCs that
support it.
It comes with support for both PIO and Single DMA modes and samples the
clock from the extres clk API.

Submitted by: Artur Rojek <ar@semihalf.com>
Reviewed by: manu, mmel, kibab
Obtained from: Semihalf
Sponsored by: Alstom Group
Differential Revision: https://reviews.freebsd.org/D26153

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Warner Losh [Tue, 1 Sep 2020 16:13:09 +0000 (16:13 +0000)]

Bump date for r365052

Unnamed repository; edit this file 'description' to name the repository.

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