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Date: Sun, 22 Dec 2019 11:43:12 +0200 From: Baruch Siach <baruch@...s.co.il> To: Vivien Didelot <vivien.didelot@...il.com> Cc: Andrew Lunn <andrew@...n.ch>, Marek BehĂșn <marek.behun@....cz>, netdev@...r.kernel.org, Denis Odintsov <d.odintsov@...viangames.com> Subject: Re: [PATCH] net: dsa: mv88e6xxx: force cmode write on 6141/6341 Hi Vivien, On Fri, Dec 20 2019, Vivien Didelot wrote: > On Thu, 19 Dec 2019 11:48:22 +0200, Baruch Siach <baruch@...s.co.il> wrote: >> mv88e6xxx_port_set_cmode() relies on cmode stored in struct >> mv88e6xxx_port to skip cmode update when the requested value matches the >> cached value. It turns out that mv88e6xxx_port_hidden_write() might >> change the port cmode setting as a side effect, so we can't rely on the >> cached value to determine that cmode update in not necessary. >> >> Force cmode update in mv88e6341_port_set_cmode(), to make >> serdes configuration work again. Other mv88e6xxx_port_set_cmode() >> callers keep the current behaviour. >> >> This fixes serdes configuration of the 6141 switch on SolidRun Clearfog >> GT-8K. >> >> Fixes: 7a3007d22e8 ("net: dsa: mv88e6xxx: fully support SERDES on Topaz family") >> Reported-by: Denis Odintsov <d.odintsov@...viangames.com> >> Signed-off-by: Baruch Siach <baruch@...s.co.il> > > Andrew, > > We tend to avoid caching values in the mv88e6xxx driver the more we can and > query the hardware instead to avoid errors like this. We can consider calling a > new mv88e6xxx_port_get_cmode() helper when needed (e.g. in higher level callers > like mv88e6xxx_serdes_power() and mv88e6xxx_serdes_irq_thread_fn()) and pass > the value down to the routines previously accessing chip->ports[port].cmode, > as a new argument. I can prepare a patch doing this. What do you think? I'm not sure that cmode read would always give a valid value. On 6141 I see an invalid 0x6 value after mv88e6xxx_port_hidden_write(). As I understand, this cache elimination work would target v5.6+. Would you ack this patch for v5.5-rc to fix currently broken setup? Thanks, baruch -- http://baruch.siach.name/blog/ ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@...s.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
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