diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_i2c.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_i2c.c | 70 |
1 files changed, 59 insertions, 11 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c index 97606c1be70d..bef32b7c248e 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -361,15 +361,39 @@ gmbus_wait_idle(struct drm_i915_private *dev_priv) return ret; } +static inline +unsigned int gmbus_max_xfer_size(struct drm_i915_private *dev_priv) +{ + return INTEL_GEN(dev_priv) >= 9 ? GEN9_GMBUS_BYTE_COUNT_MAX : + GMBUS_BYTE_COUNT_MAX; +} + static int gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv, unsigned short addr, u8 *buf, unsigned int len, - u32 gmbus1_index) + u32 gmbus0_reg, u32 gmbus1_index) { + unsigned int size = len; + bool burst_read = len > gmbus_max_xfer_size(dev_priv); + bool extra_byte_added = false; + + if (burst_read) { + /* + * As per HW Spec, for 512Bytes need to read extra Byte and + * Ignore the extra byte read. + */ + if (len == 512) { + extra_byte_added = true; + len++; + } + size = len % 256 + 256; + I915_WRITE_FW(GMBUS0, gmbus0_reg | GMBUS_BYTE_CNT_OVERRIDE); + } + I915_WRITE_FW(GMBUS1, gmbus1_index | GMBUS_CYCLE_WAIT | - (len << GMBUS_BYTE_COUNT_SHIFT) | + (size << GMBUS_BYTE_COUNT_SHIFT) | (addr << GMBUS_SLAVE_ADDR_SHIFT) | GMBUS_SLAVE_READ | GMBUS_SW_RDY); while (len) { @@ -382,17 +406,34 @@ gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv, val = I915_READ_FW(GMBUS3); do { + if (extra_byte_added && len == 1) + break; + *buf++ = val & 0xff; val >>= 8; } while (--len && ++loop < 4); + + if (burst_read && len == size - 4) + /* Reset the override bit */ + I915_WRITE_FW(GMBUS0, gmbus0_reg); } return 0; } +/* + * HW spec says that 512Bytes in Burst read need special treatment. + * But it doesn't talk about other multiple of 256Bytes. And couldn't locate + * an I2C slave, which supports such a lengthy burst read too for experiments. + * + * So until things get clarified on HW support, to avoid the burst read length + * in fold of 256Bytes except 512, max burst read length is fixed at 767Bytes. + */ +#define INTEL_GMBUS_BURST_READ_MAX_LEN 767U + static int gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, - u32 gmbus1_index) + u32 gmbus0_reg, u32 gmbus1_index) { u8 *buf = msg->buf; unsigned int rx_size = msg->len; @@ -400,10 +441,13 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, int ret; do { - len = min(rx_size, GMBUS_BYTE_COUNT_MAX); + if (HAS_GMBUS_BURST_READ(dev_priv)) + len = min(rx_size, INTEL_GMBUS_BURST_READ_MAX_LEN); + else + len = min(rx_size, gmbus_max_xfer_size(dev_priv)); - ret = gmbus_xfer_read_chunk(dev_priv, msg->addr, - buf, len, gmbus1_index); + ret = gmbus_xfer_read_chunk(dev_priv, msg->addr, buf, len, + gmbus0_reg, gmbus1_index); if (ret) return ret; @@ -462,7 +506,7 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg, int ret; do { - len = min(tx_size, GMBUS_BYTE_COUNT_MAX); + len = min(tx_size, gmbus_max_xfer_size(dev_priv)); ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len, gmbus1_index); @@ -491,7 +535,8 @@ gmbus_is_index_xfer(struct i2c_msg *msgs, int i, int num) } static int -gmbus_index_xfer(struct drm_i915_private *dev_priv, struct i2c_msg *msgs) +gmbus_index_xfer(struct drm_i915_private *dev_priv, struct i2c_msg *msgs, + u32 gmbus0_reg) { u32 gmbus1_index = 0; u32 gmbus5 = 0; @@ -509,7 +554,8 @@ gmbus_index_xfer(struct drm_i915_private *dev_priv, struct i2c_msg *msgs) I915_WRITE_FW(GMBUS5, gmbus5); if (msgs[1].flags & I2C_M_RD) - ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus1_index); + ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus0_reg, + gmbus1_index); else ret = gmbus_xfer_write(dev_priv, &msgs[1], gmbus1_index); @@ -544,10 +590,12 @@ retry: for (; i < num; i += inc) { inc = 1; if (gmbus_is_index_xfer(msgs, i, num)) { - ret = gmbus_index_xfer(dev_priv, &msgs[i]); + ret = gmbus_index_xfer(dev_priv, &msgs[i], + gmbus0_source | bus->reg0); inc = 2; /* an index transmission is two msgs */ } else if (msgs[i].flags & I2C_M_RD) { - ret = gmbus_xfer_read(dev_priv, &msgs[i], 0); + ret = gmbus_xfer_read(dev_priv, &msgs[i], + gmbus0_source | bus->reg0, 0); } else { ret = gmbus_xfer_write(dev_priv, &msgs[i], 0); } |