Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] hwmon: xgene: access mailbox as RAM | Date | Fri, 09 Sep 2016 21:58:49 +0200 |
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On Friday, September 9, 2016 12:24:32 PM CEST Hoan Tran wrote: > On Fri, Sep 9, 2016 at 8:38 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > The newly added hwmon driver fails to build in an allmodconfig > > index bc78a5d10182..e834dfb3acca 100644 > > --- a/drivers/hwmon/xgene-hwmon.c > > +++ b/drivers/hwmon/xgene-hwmon.c > > @@ -34,7 +34,8 @@ > > #include <linux/module.h> > > #include <linux/of.h> > > #include <linux/platform_device.h> > > -#include <acpi/acpi_io.h> > > +#include <linux/io.h> > > Alphabetical order. > > > struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr; > > - void *ptr = generic_comm_base + 1; > > + u32 *ptr = (void*)(generic_comm_base + 1); > > Space before "*".
Ok.
> > @@ -652,9 +653,9 @@ static int xgene_hwmon_probe(struct platform_device *pdev) > > */ > > ctx->comm_base_addr = cppc_ss->base_address; > > if (ctx->comm_base_addr) { > > - ctx->pcc_comm_addr = > > - acpi_os_ioremap(ctx->comm_base_addr, > > - cppc_ss->length); > > + ctx->pcc_comm_addr = memremap(ctx->comm_base_addr, > > + cppc_ss->length, > > + MEMREMAP_WT); > > It should be MEMREMAP_WB. As mailbox shared memory is on RAM and our > co-processor is also in the coherency domain.
Right, I was wondering about this, since I could not figure out what the other side is (hardware, service processor or firmware). So MEMREMAP_WB makes sense here.
Two more questions:
* Any comment on the byte ordering of the data in this line:
/* Copy the message to the PCC comm space */ for (i = 0; i < sizeof(struct slimpro_resp_msg) / 4; i++) - writel_relaxed(msg[i], ptr + i * 4); + WRITE_ONCE(ptr[i], cpu_to_le32(msg[i]));
This assumes that the old code was correct even when running on big-endian kernels and the message data consists of 32-bit data words. If the message has some other format instead, we would need to treat this as a byte stream and not do swapping here but instead do it (if any) in the code that reads or writes the actual data here.
* Are you sure you don't need any smp_rmb()/smp_wmb() barriers between the accesses?
Arnd
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