Re: [PATCH] ia64: fix barrier placement for write* / dma mapping

2018-08-01 Thread Sinan Kaya
On 8/1/2018 12:29 AM, Christoph Hellwig wrote: I asked this question to Tony Luck before. If I remember right, his answer was: CPU guarantees outstanding writes to be flushed when a register write instruction is executed and an additional barrier instruction is not needed. That would be great.

Re: [PATCH] ia64: fix barrier placement for write* / dma mapping

2018-08-01 Thread Christoph Hellwig
On Tue, Jul 31, 2018 at 11:41:23PM -0700, ok...@codeaurora.org wrote: > I asked this question to Tony Luck before. If I remember right, > his answer was: > > CPU guarantees outstanding writes to be flushed when a register write > instruction is executed and an additional barrier instruction is not

Re: [PATCH] ia64: fix barrier placement for write* / dma mapping

2018-08-01 Thread okaya
+ my new email On 2018-07-31 10:20, Christoph Hellwig wrote: memory-barriers.txt has been updated with the following requirement. "When using writel(), a prior wmb() is not needed to guarantee that the cache coherent memory writes have completed before writing to the MMIO region." The current

[PATCH] ia64: fix barrier placement for write* / dma mapping

2018-07-31 Thread Christoph Hellwig
memory-barriers.txt has been updated with the following requirement. "When using writel(), a prior wmb() is not needed to guarantee that the cache coherent memory writes have completed before writing to the MMIO region." The current writeX() and iowriteX() implementations on ia64 are not