At some point, the transmit descriptor chain end interrupt (TXDCEINT)
was turned on. This is a mistake; and it damages small packet
transmit performance, as it results in a huge storm of interrupts.
Turn it off.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Although the previous patch resolved issues with hangs when the
RX ram full interrupt is encountered, there are still situations
where lots of RX ramfull interrupts arrive, resulting in a noisy
log in syslog. There is no need for this.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch fixes a rare deadlock that can occur when the kernel
is not able to empty out the RX ring quickly enough. Below follows
a detailed description of the bug and the fix.
As long as the OS can empty out the RX buffers at a rate faster than
the hardware can fill them, there is no problem. If, for some reason,
the OS fails to empty the RX ring fast enough, the hardware GDACTDPA
pointer will catch up to the head, notice the not-empty condition,
ad stop. However, RX packets may still continue arriving on the wire.
The spidernet chip can save some limited number of these in local RAM.
When this local ram fills up, the spider chip will issue an interrupt
indicating this (GHIINT0STS will show ERRINT, and the GRMFLLINT bit
will be set in GHIINT1STS). When te RX ram full condition occurs,
a certain bug/feature is triggered that has to be specially handled.
This section describes the special handling for this condition.
When the OS finally has a chance to run, it will empty out the RX ring.
In particular, it will clear the descriptor on which the hardware had
stopped. However, once the hardware has decided that a certain
descriptor is invalid, it will not restart at that descriptor; instead
it will restart at the next descr. This potentially will lead to a
deadlock condition, as the tail pointer will be pointing at this descr,
which, from the OS point of view, is empty; the OS will be waiting for
this descr to be filled. However, the hardware has skipped this descr,
and is filling the next descrs. Since the OS doesn't see this, there
is a potential deadlock, with the OS waiting for one descr to fill,
while the hardware is waiting for a differen set of descrs to become
empty.
A call to show_rx_chain() at this point indicates the nature of the
problem. A typical print when the network is hung shows the following:
net eth1: Spider RX RAM full, incoming packets might be discarded!
net eth1: Total number of descrs=256
net eth1: Chain tail located at descr=255
net eth1: Chain head is at 255
net eth1: HW curr desc (GDACTDPA) is at 0
net eth1: Have 1 descrs with stat=xa0800000
net eth1: HW next desc (GDACNEXTDA) is at 1
net eth1: Have 127 descrs with stat=x40800101
net eth1: Have 1 descrs with stat=x40800001
net eth1: Have 126 descrs with stat=x40800101
net eth1: Last 1 descrs with stat=xa0800000
Both the tail and head pointers are pointing at descr 255, which is
marked xa... which is "empty". Thus, from the OS point of view, there
is nothing to be done. In particular, there is the implicit assumption
that everything in front of the "empty" descr must surely also be empty,
as explained in the last section. The OS is waiting for descr 255 to
become non-empty, which, in this case, will never happen.
The HW pointer is at descr 0. This descr is marked 0x4.. or "full".
Since its already full, the hardware can do nothing more, and thus has
halted processing. Notice that descrs 0 through 254 are all marked
"full", while descr 254 and 255 are empty. (The "Last 1 descrs" is
descr 254, since tail was at 255.) Thus, the system is deadlocked,
and there can be no forward progress; the OS thinks there's nothing
to do, and the hardware has nowhere to put incoming data.
This bug/feature is worked around with the spider_net_resync_head_ptr()
routine. When the driver receives RX interrupts, but an examination
of the RX chain seems to show it is empty, then it is probable that
the hardware has skipped a descr or two (sometimes dozens under heavy
network conditions). The spider_net_resync_head_ptr() subroutine will
search the ring for the next full descr, and the driver will resume
operations there. Since this will leave "holes" in the ring, there
is also a spider_net_resync_tail_ptr() that will skip over such holes.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch separates the hardware descriptor state from the
driver descriptor state, per (old) suggestion from Ben Herrenschmidt.
This compiles and boots and seems to work.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Cc: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This moves the medium variable into the spidernet card structure.
It renames the GMII_ variables to BCM54XX specific ones.
Signed-off-by: Jens Osterkamp <jens@de.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds or changes some HW specific settings for spider_net on
Celleb.
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add auto negotiation support for Celleb.
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Get rid of the rxramfull tasklet, and let the NAPI poll routine
deal with this situation. (The rxramfull interrupt is simply
stating that the h/w has run out of room for incoming packets).
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds net_ratelimit to many of the printks in order to
limit extraneous warning messages (created in response to Bug 28554).
This patch supercedes all previous ratelimit patches.
This has been tested, please apply.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <jlinas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The current driver code performs 512 DMA mappings of a bunch of
32-byte ring descriptor structures. This is silly, as they are
all in contiguous memory. This patch changes the code to
dma_map_coherent() each rx/tx ring as a whole.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Correct a problem seen on later kernels running the NetPIPE application.
Specifically, NetPIPE would begin running very slowly at the 1533 packet
size. It was determined that Spidernet slowed with an idle DMA engine.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
In an earlier patch, code was added to pad packets that were less that
ETH_ZLEN (60) bytes using the skb_pad function. This has caused hangs when
accessing certain NFS mounted file systems. This patch removes the check
and solves the NFS problem. The driver, with this patch, has been tested
extensively. Please apply.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Cc: Stephen Hemminger <shemminger@osdl.org>
Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Cosmetic patch: give the variable holding the numer of descriptors
a more descriptive name, so to avoid confusion.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Implement basic low-watermark support for the transmit queue.
Hardware low-watermarks allow a properly configured kernel
to continously stream data to a device and not have to handle
any interrupts at all in doing so. Correct zero-interrupt
operation can be actually observed for this driver, when the
socket buffer is made large enough.
The basic idea of a low-watermark interrupt is as follows.
The device driver queues up a bunch of packets for the hardware
to transmit, and then kicks the hardware to get it started.
As the hardware drains the queue of pending, untransmitted
packets, the device driver will want to know when the queue
is almost empty, so that it can queue some more packets.
If the queue drains down to the low waterark, then an interrupt
will be generated. However, if the kernel/driver continues
to add enough packets to keep the queue partially filled,
no interrupt will actually be generated, and the hardware
can continue streaming packets indefinitely in this mode.
The impelmentation is done by setting the DESCR_TXDESFLG flag
in one of the packets. When the hardware sees this flag, it will
interrupt the device driver. Because this flag is on a fixed
packet, rather than at fixed location in the queue, the
code below needs to move the flag as more packets are
queued up. This implementation attempts to keep the flag
at about 1/4 from "empty".
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The current receive interrupt mask sets a bogus bit that doesn't even
belong to the definition of this register. Remove it.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch fixes the names of a few fields in the DMA control
register. There is no functional change.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch increases the Burst Address alignment from 64 to 1024 in the
Spidernet driver. This improves transmit performance for large packets.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds version information as reported by
ethtool -i to the Spidernet driver.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add the ethtool -S (show statistics) feature to the Spidernet ethernet
driver. I have tested it extensively and believe it is ready to be
applied.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add ethtool -g (show ring sizes) support to the Spidernet network driver.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
With this patch TX queue descriptors are not chained per default any more.
The pointer to next descriptor is set only when next descriptor is prepaired
for transfer. Also the mechanism of checking wether Spider is ready has been
changed: it checks not for CARDOWNED flag in status of previous descriptor
but for a TXDMAENABLED flag in Spider's register.
Signed-off-by: Maxim Shchetynin <maxim@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
We found a new chip setting that we need in order
to make the driver work more reliable.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Performance optimizations, changes in these areas:
- RX and TX checksum offload
- correct maximum MTU
- don't use TX interrupts anymore, use a timer instead
- remove some superfluous barriers
- improve RX RAM full handling
From: Utz Bacher <utz.bacher@de.ibm.com>
Signed-off-by: Jens Osterkamp <jens.osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
The driver incorrectly used dma_addr_t to describe
HW structures and consequently broke when that type
was changed in 2.6.15-rc.
This changed spidernet to use u32 for 32 bit HW defined
structure elements.
From: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
This patch adds a driver for a new 1000 Mbit ethernet NIC. It is
integrated on the south bridge that is used for our Cell Blades.
The code gets the MAC address from the Open Firmware device tree, so it
won't compile on platforms other than ppc64.
This is the first public release, so I don't expect the first version to
get merged, but I'd aim for integration within the 2.6.13 time frame.
Cc: Utz Bacher <utz.bacher@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
