From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Osterried Subject: Re: [PATCH net-next 6/6] net: hamradio: remove support for DMA SCC devices Date: Mon, 2 May 2022 03:01:24 +0200 Message-ID: <692463B1-ABB4-4DBB-81EA-945B7D588A39@osterried.de> References: <20220426175436.417283-1-kuba@kernel.org> <20220426175436.417283-7-kuba@kernel.org> <20220426123941.5c6643ee@kernel.org> Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.80.82.1.1\)) Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" To: Arnd Bergmann Cc: Jakub Kicinski , linux-hams@vger.kernel.org, jreuter@yaina.de > Am 27.04.2022 um 15:27 schrieb Arnd Bergmann : > > On Tue, Apr 26, 2022 at 9:39 PM Jakub Kicinski wrote: >> >> On Tue, 26 Apr 2022 20:55:05 +0200 Thomas Osterried wrote: >>> Jakub informed, that the dmascc driver will be removed from kernel. >>> >>> I think, Jakub's descision should be discussed here on the list, by the users. >> >> Thanks a lot for the forward! >> >>> DMASCC is the "high speed DMA" driver. >>> SCC driver (also with Z8530) will be left in the kernel. >>> >>> Hmm, I cannot really understand the decision of kickoff for DMASCC, and >>> why the code "older" SCC ISA-bus cards will be kept. >> >> We are infamously bad at deciding when to retire code in the kernel, >> the arbitrary rule I used now was "does it depend on VIRT_TO_BUS". >> I figured the non-DMA SCC will go when ISA goes. > > Looking at how this driver uses virt_to_bus, I think it can trivially get > converted to isa_virt_to_bus(), which only operates on the low 16MB. Anyone has those cards SCC and DMA-SCC cards still in use and like to test? > What hardware is ax25 actually used on normally? the drivers I can see > are based on > > 6pack: serial (through tty layer) > bpqether: ethernet > dmascc: isa (with DMA) > scc: isa (without DMA) > baycom: serial (bypassing tty layer) or parport > yam: serial (bypassing tty layer) mkiss: serial (through tty layer) Speaking about the serial protocols, 6pack is more sophisticated. But kiss is more common. Personally, I'm a fan of the bpqether driver. It is so fast, because it gets the skb from the ethernet driver and just needs to pass the payload to the AX.25 stack (or vice versa, add ethernet header and pid, pass it to the ethernet driver, done). > The ISA drivers are clearly the most obsolete, as they require a 32-bit PC > or 1990s RISC workstation with ISA slots. > > The baycom and yam drivers in turn look like they could work on any > serial port but are written to assume an ISA-style onboard serial port > on a PC. You can technically still buy new machines that have those, > but the drivers should really be changed to go through the tty layer > if someone wants to use them with a USB-serial adapter or similar. Ok. Same question to our community on the mailing-list as for the (DMA)-SCC-cards: it would be interesting who is still using this hardware, while running a current kernel. vy 73, - Thomas dl9sau