From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 13 May 2014 10:43:06 +0200 Subject: [RFC][PATCH 2/2] ARM: ioremap: Add IO mapping space reused support. In-Reply-To: References: <1399861195-21087-1-git-send-email-superlibj8301@gmail.com> <5146762.jba3IJe7xt@wuerfel> Message-ID: <5026482.P9PDy29y2Y@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 13 May 2014 09:45:08 Richard Lee wrote: > > On Mon, May 12, 2014 at 3:51 PM, Arnd Bergmann wrote: > > On Monday 12 May 2014 10:19:55 Richard Lee wrote: > >> For the IO mapping, for the same physical address space maybe > >> mapped more than one time, for example, in some SoCs: > >> 0x20000000 ~ 0x20001000: are global control IO physical map, > >> and this range space will be used by many drivers. > >> And then if each driver will do the same ioremap operation, we > >> will waste to much malloc virtual spaces. > >> > >> This patch add IO mapping space reused support. > >> > >> Signed-off-by: Richard Lee > > > > What happens if the first driver then unmaps the area? > > > > If the first driver will unmap the area, it shouldn't do any thing > except decreasing the 'used' counter. Ah, for some reason I didn't see your first patch that introduces that counter. Arnd