From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Date: Mon, 19 Nov 2012 22:04:44 +0000 Subject: Re: [PATCH 0/5] OMAPFB: use dma_alloc instead of omap's vram Message-Id: <20121119220443.GD18567@atomide.com> List-Id: References: <1352715906-16946-1-git-send-email-tomi.valkeinen@ti.com> <20121112225037.GU6801@atomide.com> <50A601FA.5060401@ti.com> In-Reply-To: <50A601FA.5060401@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org * Tomi Valkeinen [121116 01:08]: > Hi Tony, > > On 2012-11-13 00:50, Tony Lindgren wrote: > > * Tomi Valkeinen [121112 02:27]: > >> Hi, > >> > >> This series changes omapfb to use standard dma_alloc funcs instead of omap > >> specific vram allocator. This let's us remove the omap vram allocator, making > >> omapfb platform independent. > >> > >> However, note that using standard dma funcs causes the following downsides: > >> > >> 1) dma_alloc_attrs doesn't let us allocate at certain physical address. > >> However, this should not be a problem as this feature of vram allocator > >> is only used when reserving the framebuffer that was initialized by the > >> bootloader, and we don't currently support "passing" a framebuffer from > >> the bootloader to the kernel anyway. > >> > >> 2) dma_alloc_attrs, as of now, always ioremaps the allocated area, and > >> we don't need the ioremap when using VRFB. This patch uses > >> DMA_ATTR_NO_KERNEL_MAPPING for the allocation, but the flag is currently > >> not operational. > >> > >> 3) OMAPFB_GET_VRAM_INFO ioctl cannot return real values anymore. I > >> changed the ioctl to return 64M for all the values, which, I hope, the > >> applications will interpret as "there's enough vram". > >> > >> 4) "vram" kernel parameter to define how much ram to reserve for video use no > >> longer works. The user needs to enable CMA and use "cma" parameter. > > > > Great, thanks for fixing these. Could you please queue these into > > a separate branch against v3.7-rc5 that I can also merge into > > omap-for-v3.8/cleanup-headers-prepare-multiplatform-v3? > > Should we enable CMA by default in omap2plus_defconfig? And perhaps on > omap1 also? Yes if that's now needed for DSS. > I have to say I don't know the details of the dma allocation, but afaik > there are no drawbacks with CMA. Although it is still marked > EXPERIMENTAL in the kconfig... I guess that's still fine as that's what we're supposed to use :) Regards, Tony