On 2018-04-05 03:00, Arnd Bergmann wrote:
On Thu, Apr 5, 2018 at 1:58 AM, Sinan Kaya <okaya@xxxxxxxxxxxxxx>
wrote:
Looks good, but I'd change the comments to ones that document exactly
what those barriers are for:
+#ifndef __io_ar
+#ifdef rmb
+/* prefer rmb() as the default implementation of __io_ar() if
supported */
+#define __io_ar() rmb()
/*
* prevent prefetching of coherent DMA data ahead of a dma-complete */
+#ifndef __io_bw
+#ifdef wmb
+/* prefer wmb() as the default implementation of __io_bw() if
supported */
+#define __io_bw() wmb()
+#else
/* flush writes to coherent DMA data before possibly triggering a DMA
read */
+#ifndef __io_aw
+#define __io_aw() barrier()
+#endif
/* serialize device access against a spin_unlock, usually handled there
*/
I will add these and post the next version.
The other four patches look perfect already. What's the timing we need
for
these patches? Are they 4.18 material, or do we need them in 4.17 and
stable kernels to work around known bugs?
I was hoping to get all arch stuff in for 4.17.
Driver developers started removing redundant wmb().
Arnd
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