On Mon 2017-10-23 14:16:40, Linus Walleij wrote: > On Mon, Oct 23, 2017 at 11:31 AM, Pavel Machek <[email protected]> wrote: > > >> > Thinkpad X220... how do I tell if I was using them? I believe so, > >> > because I uncovered bug in them before. > >> > >> You are certainly using bounce buffers. What does lspci -knn show? > > > > Here is the output: > > 0d:00.0 System peripheral [0880]: Ricoh Co Ltd PCIe SDXC/MMC Host > > Controller [1180:e823] (rev 07) > > Subsystem: Lenovo Device [17aa:21da] > > Kernel driver in use: sdhci-pci > > So that is a Ricoh driver, one of the few that was supposed to benefit > from bounce buffers. > > Except that if you actually turned it on: > > [10994.302196] kworker/2:1: page allocation failure: order:4, > so it doesn't have enough memory to use these bounce buffers > anyway.
Well, look at archives: driver failed completely when allocation failed.
> I'm now feel it was the right thing to delete them.
Which means I may have been geting benefit -- when it worked. I
believe solution is to allocate at driver probing time.
(OTOH ... SPI is slow compared to rest of the system, right? Where
does the benefit come from?)
Pavel
--
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