On Fri, Dec 02, 2022 at 04:12:01PM +0100, Michael Walle wrote:
> At least the GPY215B and GPY215C has a bug where it is still driving the
> interrupt line (MDINT) even after the interrupt status register is read
> and its bits are cleared. This will cause an interrupt storm.
>
> Although the MDINT is multiplexed with a GPIO pin and theoretically we
> could switch the pinmux to GPIO input mode, this isn't possible because
> the access to this register will stall exactly as long as the interrupt
> line is asserted. We exploit this very fact and just read a random
> internal register in our interrupt handler. This way, it will be delayed
> until the external interrupt line is released and an interrupt storm is
> avoided.
>
> The internal register access via the mailbox was deduced by looking at
> the downstream PHY API because the datasheet doesn't mention any of
> this.
>
> Signed-off-by: Michael Walle <michael@xxxxxxxx>
> ---
> drivers/net/phy/mxl-gpy.c | 83 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 83 insertions(+)
>
> diff --git a/drivers/net/phy/mxl-gpy.c b/drivers/net/phy/mxl-gpy.c
> index 0ff7ef076072..20e610dda891 100644
> --- a/drivers/net/phy/mxl-gpy.c
> +++ b/drivers/net/phy/mxl-gpy.c
> @@ -9,6 +9,7 @@
> #include <linux/module.h>
> #include <linux/bitfield.h>
> #include <linux/hwmon.h>
> +#include <linux/mutex.h>
> #include <linux/phy.h>
> #include <linux/polynomial.h>
> #include <linux/netdevice.h>
> @@ -81,6 +82,14 @@
> #define VSPEC1_TEMP_STA 0x0E
> #define VSPEC1_TEMP_STA_DATA GENMASK(9, 0)
>
> +/* Mailbox */
> +#define VSPEC1_MBOX_DATA 0x5
> +#define VSPEC1_MBOX_ADDRLO 0x6
> +#define VSPEC1_MBOX_CMD 0x7
> +#define VSPEC1_MBOX_CMD_ADDRHI GENMASK(7, 0)
> +#define VSPEC1_MBOX_CMD_RD (0 << 8)
> +#define VSPEC1_MBOX_CMD_READY BIT(15)
> +
> /* WoL */
> #define VPSPEC2_WOL_CTL 0x0E06
> #define VPSPEC2_WOL_AD01 0x0E08
> @@ -88,7 +97,15 @@
> #define VPSPEC2_WOL_AD45 0x0E0A
> #define WOL_EN BIT(0)
>
> +/* Internal registers, access via mbox */
> +#define REG_GPIO0_OUT 0xd3ce00
> +
> struct gpy_priv {
> + struct phy_device *phydev;
> +
> + /* serialize mailbox acesses */
> + struct mutex mbox_lock;
> +
> static int gpy_probe(struct phy_device *phydev)
> {
> struct device *dev = &phydev->mdio.dev;
> @@ -228,7 +286,9 @@ static int gpy_probe(struct phy_device *phydev)
> priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> if (!priv)
> return -ENOMEM;
> + priv->phydev = phydev;
I don't think you use this anywhere. Maybe in one of the following
patches?
Andrew
