T4 doesn't have the Shadow copy of the register which we can read without
side effect. So don't read mbox control register for T4 adapter
Signed-off-by: Hariprasad Shenai <haripra...@chelsio.com>
---
drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
index 0a87a32..b4ace19 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
@@ -1128,18 +1128,26 @@ static const struct file_operations devlog_fops = {
static int mbox_show(struct seq_file *seq, void *v)
{
static const char * const owner[] = { "none", "FW", "driver",
- "unknown" };
+ "unknown", "<unread>" };
int i;
unsigned int mbox = (uintptr_t)seq->private & 7;
struct adapter *adap = seq->private - mbox;
void __iomem *addr = adap->regs + PF_REG(mbox, CIM_PF_MAILBOX_DATA_A);
- unsigned int ctrl_reg = (is_t4(adap->params.chip)
- ? CIM_PF_MAILBOX_CTRL_A
- : CIM_PF_MAILBOX_CTRL_SHADOW_COPY_A);
- void __iomem *ctrl = adap->regs + PF_REG(mbox, ctrl_reg);
- i = MBOWNER_G(readl(ctrl));
+ /* For T4 we don't have a shadow copy of the Mailbox Control register.
+ * And since reading that real register causes a side effect of
+ * granting ownership, we're best of simply not reading it at all.
+ */
+ if (is_t4(adap->params.chip)) {
+ i = 4; /* index of "<unread>" */
+ } else {
+ unsigned int ctrl_reg = CIM_PF_MAILBOX_CTRL_SHADOW_COPY_A;
+ void __iomem *ctrl = adap->regs + PF_REG(mbox, ctrl_reg);
+
+ i = MBOWNER_G(readl(ctrl));
+ }
+
seq_printf(seq, "mailbox owned by %s\n\n", owner[i]);
for (i = 0; i < MBOX_LEN; i += 8)
--
2.3.4
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