target/linux/mvebu/patches-4.9/406-net-phy-improve-phylib-correctness-for-non-autoneg-s.patch

   1 From: Russell King <rmk+kernel@armlinux.org.uk>
   2 Date: Thu, 5 Jan 2017 16:32:14 +0000
   3 Subject: [PATCH] net: phy: improve phylib correctness for non-autoneg
   4  settings
   5
   6 phylib has some undesirable behaviour when forcing a link mode through
   7 ethtool.  phylib uses this code:
   8
   9         idx = phy_find_valid(phy_find_setting(phydev->speed, phydev->duplex),
  10                         features);
  11
  12 to find an index in the settings table.  phy_find_setting() starts at
  13 index 0, and scans upwards looking for an exact speed and duplex match.
  14 When it doesn't find it, it returns MAX_NUM_SETTINGS - 1, which is
  15 10baseT-Half duplex.
  16
  17 phy_find_valid() then scans from the point (and effectively only checks
  18 one entry) before bailing out, returning MAX_NUM_SETTINGS - 1.
  19
  20 phy_sanitize_settings() then sets ->speed to SPEED_10 and ->duplex to
  21 DUPLEX_HALF whether or not 10baseT-Half is supported or not.  This goes
  22 against all the comments against these functions, and 10baseT-Half may
  23 not even be supported by the hardware.
  24
  25 Rework these functions, introducing a new method of scanning the table.
  26 There are two modes of lookup that phylib wants: exact, and inexact.
  27
  28 - in exact mode, we return either an exact match or failure
  29 - in inexact mode, we return an exact match if it exists, a match at
  30   the highest speed that is not greater than the requested speed
  31   (ignoring duplex), or failing that, the lowest supported speed, or
  32   failure.
  33
  34 The biggest difference is that we always check whether the entry is
  35 supported before further consideration, so all unsupported entries are
  36 not considered as candidates.
  37
  38 This results in arguably saner behaviour, better matches the comments,
  39 and is probably what users would expect.
  40
  41 This becomes important as ethernet speeds increase, PHYs exist which do
  42 not support the 10Mbit speeds, and half-duplex is likely to become
  43 obsolete - it's already not even an option on 10Gbit and faster links.
  44
  45 Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
  46 ---
  47
  48 --- a/drivers/net/phy/phy.c
  49 +++ b/drivers/net/phy/phy.c
  50 @@ -160,7 +160,9 @@ struct phy_setting {
  51         u32 setting;
  52  };
  53
  54 -/* A mapping of all SUPPORTED settings to speed/duplex */
  55 +/* A mapping of all SUPPORTED settings to speed/duplex.  This table
  56 + * must be grouped by speed and sorted in descending match priority
  57 + * - iow, descending speed. */
  58  static const struct phy_setting settings[] = {
  59         {
  60                 .speed = SPEED_10000,
  61 @@ -219,45 +221,70 @@ static const struct phy_setting settings
  62         },
  63  };
  64
  65 -#define MAX_NUM_SETTINGS ARRAY_SIZE(settings)
  66 -
  67  /**
  68 - * phy_find_setting - find a PHY settings array entry that matches speed & duplex
  69 + * phy_lookup_setting - lookup a PHY setting
  70   * @speed: speed to match
  71   * @duplex: duplex to match
  72 + * @feature: allowed link modes
  73 + * @exact: an exact match is required
  74 + *
  75 + * Search the settings array for a setting that matches the speed and
  76 + * duplex, and which is supported.
  77 + *
  78 + * If @exact is unset, either an exact match or %NULL for no match will
  79 + * be returned.
  80   *
  81 - * Description: Searches the settings array for the setting which
  82 - *   matches the desired speed and duplex, and returns the index
  83 - *   of that setting.  Returns the index of the last setting if
  84 - *   none of the others match.
  85 + * If @exact is set, an exact match, the fastest supported setting at
  86 + * or below the specified speed, the slowest supported setting, or if
  87 + * they all fail, %NULL will be returned.
  88   */
  89 -static inline unsigned int phy_find_setting(int speed, int duplex)
  90 +static const struct phy_setting *
  91 +phy_lookup_setting(int speed, int duplex, u32 features, bool exact)
  92  {
  93 -       unsigned int idx = 0;
  94 +       const struct phy_setting *p, *match = NULL, *last = NULL;
  95 +       int i;
  96
  97 -       while (idx < ARRAY_SIZE(settings) &&
  98 -              (settings[idx].speed != speed || settings[idx].duplex != duplex))
  99 -               idx++;
 100 +       for (i = 0, p = settings; i < ARRAY_SIZE(settings); i++, p++) {
 101 +               if (p->setting & features) {
 102 +                       last = p;
 103 +                       if (p->speed == speed && p->duplex == duplex) {
 104 +                               /* Exact match for speed and duplex */
 105 +                               match = p;
 106 +                               break;
 107 +                       } else if (!exact) {
 108 +                               if (!match && p->speed <= speed)
 109 +                                       /* Candidate */
 110 +                                       match = p;
 111 +
 112 +                               if (p->speed < speed)
 113 +                                       break;
 114 +                       }
 115 +               }
 116 +       }
 117
 118 -       return idx < MAX_NUM_SETTINGS ? idx : MAX_NUM_SETTINGS - 1;
 119 +       if (!match && !exact)
 120 +               match = last;
 121 +
 122 +       return match;
 123  }
 124
 125  /**
 126 - * phy_find_valid - find a PHY setting that matches the requested features mask
 127 - * @idx: The first index in settings[] to search
 128 - * @features: A mask of the valid settings
 129 + * phy_find_valid - find a PHY setting that matches the requested parameters
 130 + * @speed: desired speed
 131 + * @duplex: desired duplex
 132 + * @supported: mask of supported link modes
 133   *
 134 - * Description: Returns the index of the first valid setting less
 135 - *   than or equal to the one pointed to by idx, as determined by
 136 - *   the mask in features.  Returns the index of the last setting
 137 - *   if nothing else matches.
 138 + * Locate a supported phy setting that is, in priority order:
 139 + * - an exact match for the specified speed and duplex mode
 140 + * - a match for the specified speed, or slower speed
 141 + * - the slowest supported speed
 142 + * Returns the matched phy_setting entry, or %NULL if no supported phy
 143 + * settings were found.
 144   */
 145 -static inline unsigned int phy_find_valid(unsigned int idx, u32 features)
 146 +static const struct phy_setting *
 147 +phy_find_valid(int speed, int duplex, u32 supported)
 148  {
 149 -       while (idx < MAX_NUM_SETTINGS && !(settings[idx].setting & features))
 150 -               idx++;
 151 -
 152 -       return idx < MAX_NUM_SETTINGS ? idx : MAX_NUM_SETTINGS - 1;
 153 +       return phy_lookup_setting(speed, duplex, supported, false);
 154  }
 155
 156  /**
 157 @@ -271,12 +298,7 @@ static inline unsigned int phy_find_vali
 158   */
 159  static inline bool phy_check_valid(int speed, int duplex, u32 features)
 160  {
 161 -       unsigned int idx;
 162 -
 163 -       idx = phy_find_valid(phy_find_setting(speed, duplex), features);
 164 -
 165 -       return settings[idx].speed == speed && settings[idx].duplex == duplex &&
 166 -               (settings[idx].setting & features);
 167 +       return !!phy_lookup_setting(speed, duplex, features, true);
 168  }
 169
 170  /**
 171 @@ -289,18 +311,22 @@ static inline bool phy_check_valid(int s
 172   */
 173  static void phy_sanitize_settings(struct phy_device *phydev)
 174  {
 175 +       const struct phy_setting *setting;
 176         u32 features = phydev->supported;
 177 -       unsigned int idx;
 178
 179         /* Sanitize settings based on PHY capabilities */
 180         if ((features & SUPPORTED_Autoneg) == 0)
 181                 phydev->autoneg = AUTONEG_DISABLE;
 182
 183 -       idx = phy_find_valid(phy_find_setting(phydev->speed, phydev->duplex),
 184 -                       features);
 185 -
 186 -       phydev->speed = settings[idx].speed;
 187 -       phydev->duplex = settings[idx].duplex;
 188 +       setting = phy_find_valid(phydev->speed, phydev->duplex, features);
 189 +       if (setting) {
 190 +               phydev->speed = setting->speed;
 191 +               phydev->duplex = setting->duplex;
 192 +       } else {
 193 +               /* We failed to find anything (no supported speeds?) */
 194 +               phydev->speed = SPEED_UNKNOWN;
 195 +               phydev->duplex = DUPLEX_UNKNOWN;
 196 +       }
 197  }
 198
 199  /**