On 2019/10/22 上午12:31, Simon Horman wrote:
On Mon, Oct 21, 2019 at 05:55:33PM +0800, Zhu, Lingshan wrote:
On 10/16/2019 5:53 PM, Simon Horman wrote:
Hi Zhu,
thanks for your patch.
On Wed, Oct 16, 2019 at 09:10:40AM +0800, Zhu Lingshan wrote:
...
+static void ifcvf_read_dev_config(struct ifcvf_hw *hw, u64 offset,
+ void *dst, int length)
+{
+ int i;
+ u8 *p;
+ u8 old_gen, new_gen;
+
+ do {
+ old_gen = ioread8(&hw->common_cfg->config_generation);
+
+ p = dst;
+ for (i = 0; i < length; i++)
+ *p++ = ioread8((u8 *)hw->dev_cfg + offset + i);
+
+ new_gen = ioread8(&hw->common_cfg->config_generation);
+ } while (old_gen != new_gen);
Would it be wise to limit the number of iterations of the loop above?
Thanks but I don't quite get it. This is used to make sure the function
would get the latest config.
I am worried about the possibility that it will loop forever.
Could that happen?
...
My understanding is that the function here is similar to virtio config
generation [1]. So this can only happen for a buggy hardware.
Thanks
[1]
https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html
Section 2.4.1
+static void io_write64_twopart(u64 val, u32 *lo, u32 *hi)
+{
+ iowrite32(val & ((1ULL << 32) - 1), lo);
+ iowrite32(val >> 32, hi);
+}
I see this macro is also in virtio_pci_modern.c
Assuming lo and hi aren't guaranteed to be sequential
and thus iowrite64_hi_lo() cannot be used perhaps
it would be good to add a common helper somewhere.
Thanks, I will try after this IFC patchwork, I will cc you.
Thanks.
...
