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From: David Miller <davem@davemloft.net>
To: marex@denx.de
Cc: netdev@vger.kernel.org, lukas@wunner.de, ynezz@true.cz,
	yuehaibing@huawei.com
Subject: Re: [PATCH V6 00/20] net: ks8851: Unify KS8851 SPI and MLL drivers
Date: Sat, 16 May 2020 19:02:25 -0700 (PDT)	[thread overview]
Message-ID: <20200516.190225.342589110126932388.davem@davemloft.net> (raw)
In-Reply-To: <20200517003354.233373-1-marex@denx.de>

From: Marek Vasut <marex@denx.de>
Date: Sun, 17 May 2020 02:33:34 +0200

> The KS8851SNL/SNLI and KS8851-16MLL/MLLI/MLLU are very much the same pieces
> of silicon, except the former has an SPI interface, while the later has a
> parallel bus interface. Thus far, Linux has two separate drivers for each
> and they are diverging considerably.
> 
> This series unifies them into a single driver with small SPI and parallel
> bus specific parts. The approach here is to first separate out the SPI
> specific parts into a separate file, then add parallel bus accessors in
> another separate file and then finally remove the old parallel bus driver.
> The reason for replacing the old parallel bus driver is because the SPI
> bus driver is much higher quality.

What strikes me in these changes is all of the new indirect jumps in
the fast paths of TX and RX packet processing.  It's just too much for
my eyes. :-)

Especially in the presence of Spectre mitigations, these costs are
quite non-trivial.

Seriously, I would recommend that instead of having these small
indirect helpers, just inline the differences into two instances of
the RX interrupt and the TX handler.

  parent reply	other threads:[~2020-05-17  2:02 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-17  0:33 [PATCH V6 00/20] net: ks8851: Unify KS8851 SPI and MLL drivers Marek Vasut
2020-05-17  0:33 ` [PATCH V6 01/20] net: ks8851: Factor out spi->dev in probe()/remove() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 02/20] net: ks8851: Rename ndev to netdev in probe Marek Vasut
2020-05-17  0:33 ` [PATCH V6 03/20] net: ks8851: Replace dev_err() with netdev_err() in IRQ handler Marek Vasut
2020-05-17  0:33 ` [PATCH V6 04/20] net: ks8851: Pass device node into ks8851_init_mac() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 05/20] net: ks8851: Use devm_alloc_etherdev() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 06/20] net: ks8851: Use dev_{get,set}_drvdata() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 07/20] net: ks8851: Remove ks8851_rdreg32() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 08/20] net: ks8851: Use 16-bit writes to program MAC address Marek Vasut
2020-05-17  0:33 ` [PATCH V6 09/20] net: ks8851: Use 16-bit read of RXFC register Marek Vasut
2020-05-17 19:44   ` Andrew Lunn
2020-05-17 20:02     ` Marek Vasut
2020-05-17  0:33 ` [PATCH V6 10/20] net: ks8851: Factor out bus lock handling Marek Vasut
2020-05-17  0:33 ` [PATCH V6 11/20] net: ks8851: Factor out SKB receive function Marek Vasut
2020-05-17  0:33 ` [PATCH V6 12/20] net: ks8851: Split out SPI specific entries in struct ks8851_net Marek Vasut
2020-05-17  0:33 ` [PATCH V6 13/20] net: ks8851: Split out SPI specific code from probe() and remove() Marek Vasut
2020-05-17  0:33 ` [PATCH V6 14/20] net: ks8851: Factor out TX work flush function Marek Vasut
2020-05-17  0:33 ` [PATCH V6 15/20] net: ks8851: Permit overridding interrupt enable register Marek Vasut
2020-05-17  0:33 ` [PATCH V6 16/20] net: ks8851: Implement register, FIFO, lock accessor callbacks Marek Vasut
2020-05-18 16:34   ` Jakub Kicinski
2020-05-18 17:06     ` Marek Vasut
2020-05-18 17:29       ` Jakub Kicinski
2020-05-17  0:33 ` [PATCH V6 17/20] net: ks8851: Separate SPI operations into separate file Marek Vasut
2020-05-17  0:33 ` [PATCH V6 18/20] net: ks8851: Implement Parallel bus operations Marek Vasut
2020-05-18 16:33   ` Jakub Kicinski
2020-05-17  0:33 ` [PATCH V6 19/20] net: ks8851: Remove ks8851_mll.c Marek Vasut
2020-05-17  0:33 ` [PATCH V6 20/20] net: ks8851: Drop define debug and pr_fmt() Marek Vasut
2020-05-17  2:01   ` Joe Perches
2020-05-17  2:28     ` Marek Vasut
2020-05-17  2:37       ` Joe Perches
2020-05-17  2:47         ` Marek Vasut
2020-05-17  2:55           ` Joe Perches
2020-05-18 17:07             ` Marek Vasut
2020-05-17  2:02 ` David Miller [this message]
2020-05-17  2:27   ` [PATCH V6 00/20] net: ks8851: Unify KS8851 SPI and MLL drivers Marek Vasut
2020-05-17 19:26     ` Andrew Lunn
2020-05-17 20:08       ` Marek Vasut
2020-05-17  7:13   ` Lukas Wunner
2020-05-17 12:36     ` Marek Vasut
2020-05-17 19:16     ` Andrew Lunn
2020-05-17 19:30       ` David Miller
2020-05-21 13:11         ` Marek Vasut

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