stmmac: fix PTP support for GMAC4
Due to bad management of the descriptors, when use ptp4l,
kernel panics as shown below:
-----------------------------------------------------------
Unable to handle kernel NULL pointer dereference at virtual
address 000001ac
...
Internal error: Oops: 17 [#1] SMP ARM
...
Hardware name: STi SoC with Flattened Device Tree
task: c0c05e80 task.stack: c0c00000
PC is at dwmac4_wrback_get_tx_timestamp_status+0x0/0xc
LR is at stmmac_tx_clean+0x2f8/0x4d4
-----------------------------------------------------------
In case of GMAC4 the extended descriptor pointers were
used for getting the timestamp. These are NULL for this HW,
and the normal ones must be used.
The PTP also had problems on this chip due to the bad
register management and issues on the algo adopted to
setup the PTP and getting the timestamp values from the
descriptors.
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Acked-by: Rayagond Kokatanur <rayagond@vayavyalabs.com>
Acked-by: Alexandre TORGUE <alexandre.torgue@st.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
7 files changed