From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Subject: Re: [PATCH net-next 3/5] net: mvpp2: use a data size of 10kB for Tx FIFO on port 0 Date: Sun, 4 Mar 2018 10:25:18 +0100 Message-ID: <20180304102518.1963cb8a@windsurf.home> References: <20180302154044.25204-1-antoine.tenart@bootlin.com> <20180302154044.25204-4-antoine.tenart@bootlin.com> <20180302171117.2344a893@windsurf.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Antoine Tenart , "davem@davemloft.net" , Yan Markman , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "maxime.chevallier@bootlin.com" , "gregory.clement@bootlin.com" , "miquel.raynal@bootlin.com" , Nadav Haklai , "mw@semihalf.com" To: Stefan Chulski Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hello, On Sun, 4 Mar 2018 06:29:59 +0000, Stefan Chulski wrote: > > Is there a reason to hardcode 10KB for port 0, and 3KB for the other ports ? > > Would there be use cases where the user may want different configurations > > ? > > Design requirement are 10KB TX FIFO for the 10Gb/sec and 2.5KB for the 2.5Gb/sec. What is a "design requirement" ? Is it a HW design limitation ? > Since only port 0 support 10Gb/sec and ports 1&2 support up to 2.5Gb/sec. > I don't see any reason to change this configurations. > Also TX FIFO size could be set only during probe. > > > It's just that it feels very "hardcoded" to enforce specifically those numbers. > > > > Also, does it make sense to mention the CP110 here ? Is this 19 KB limitation > > a limit of the PPv2.2 IP, or of the CP110 ? > > PPv2.2 IP is part of 110 communication processor. Thanks, I know this :-) > Next communication processor will has different Packet processor or next generation of PPv2.x > Limit is PPv2.2 TX FIFO. So, the limitation has nothing to do with CP110 really, it's just a limitation of PPv2.2, and mentioning CP110 in the comment doesn't make much sense, correct ? Best regards, Thomas -- Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering http://bootlin.com