On 06/08/2016 09:06 AM, Ivan Khoronzhuk wrote:
On 08.06.16 17:01, Ivan Khoronzhuk wrote:
Hi Schuyer,
On 07.06.16 18:26, Schuyler Patton wrote:
Hi,
On 06/07/2016 08:59 AM, Ivan Khoronzhuk wrote:
There is no reason in rx_descs property because davinici_cpdma
driver splits pool of descriptors equally between tx and rx channels.
So, this patch series makes driver to use available number of
descriptors for rx channels.
I agree with the idea of consolidating how the descriptors are
defined because of
the two variable components, number and size of the pool can be
confusing to
end users. I would like to request to change how it is being
proposed here.
I think the number of descriptors should be left in the device tree
source file as
is and remove the BD size variable and have the driver calculate the
size of the
pool necessary to support the descriptor request. From an user
perspective it is
easier I think to be able to list the number of descriptors
necessary vs. the size
of the pool.
Since the patch series points out how it is used so in the driver so
to make that
consistent is perhaps change rx_descs to total_descs.
Regards,
Schuyler
The DT entry for cpsw doesn't have property for size of the pool.
It contains only BD ram size, if you mean this. The size of the pool is
software decision. Current version of DT entry contain only rx desc
number.
That is not correct, as it depends on the size of the descriptor,
which is also
h/w parameter. The DT entry has to describe only h/w part and
shouldn't contain
driver implementation details, and I'm looking on it from this
perspective.
Besides, rx_descs describes only rx number of descriptors, that are
taken from
the same pool as tx descriptors, and setting rx desc to some new
value doesn't
mean that rest of them are freed for tx. Also, I'm going to send
series that
adds multi channel support to the driver, and in this case, splitting
of the
pool will be more sophisticated than now, after what setting those
parameters
for user (he should do this via device tree) can be even more
confusing. But,
should -> shouldn't
as it's supposed, it's software decision that shouldn't leak to the DT.
If this rx-desc field is removed how will the number of descriptors be set?
This field has been used to increase the number of descriptors so high
volume short packets are not dropped due to descriptor exhaustion. The
current
default number of 64 rx descriptors is too low for gigabit networks.
Some users
have a strong requirement for zero loss of UDP packets setting this
field to a
larger number and setting the descriptors off-chip was a means to solve
the problem.
Based on master branch
Since v1:
- separate device tree and driver patches
- return number of rx buffers from cpdma driver
Ivan Khoronzhuk (2):
net: ethernet: ti: cpsw: remove rx_descs property
Documentation: DT: cpsw: remove rx_descs property
Documentation/devicetree/bindings/net/cpsw.txt | 1 -
arch/arm/boot/dts/am33xx.dtsi | 1 -
arch/arm/boot/dts/am4372.dtsi | 1 -
arch/arm/boot/dts/dm814x.dtsi | 1 -
arch/arm/boot/dts/dra7.dtsi | 1 -
drivers/net/ethernet/ti/cpsw.c | 13 +++----------
drivers/net/ethernet/ti/cpsw.h | 1 -
drivers/net/ethernet/ti/davinci_cpdma.c | 6 ++++++
drivers/net/ethernet/ti/davinci_cpdma.h | 1 +
9 files changed, 10 insertions(+), 16 deletions(-)
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