Messages in this thread | | | Date | Sat, 20 Apr 2024 09:37:00 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH] net: phy: update fields of mii_ioctl_data for transferring C45 data. |
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On Sat, Apr 20, 2024 at 08:41:10AM +0800, renjun wang wrote: > The phy_id is used as u32 type in function mdio_phy_id_is_c45() > with the 30th bit for distinguishing C22 and C45. The reg_num is > also used as u32 type in function mdiobus_c45_read() or someplace > else. For more C45 information needed and data structure alignment > consideration, change these two fields to __u32 type which can make > user space program transferring clause 45 type information to kernel > directly.
You haven't understood the user API, and are making a change that will break existing userspace users of this API. Hence this is not acceptable.
mdio_phy_id_is_c45() is indeed for determining if the "phy_id" field in mii_ioctl_data is indicating a clause 45 transaction. This checks the following bits, defined using these macros:
#define MDIO_PHY_ID_C45 0x8000 #define MDIO_PHY_ID_PRTAD 0x03e0 #define MDIO_PHY_ID_DEVAD 0x001f
and all of these fit within the __u16.
The format used by userspace pre-dates clause 45, and bit 15 was added to indicate clause 45 along with the "prtad" in bits 9 to 5.
However, the kernel translates this data structure into something that the MDIO accessors can deal with. See for example phy_mii_ioctl().
Also note that the old method of shoe-horning clause 45 into just one set of mii bus methods has gone, meaning there is now no need to convert from mii_ioctl_data into a 32-bit reg_num.
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