On Wed, 09 May 2018, Ramalingam C <ramalinga...@intel.com> wrote:
> GMBUS HW supports 511Bytes as Max Bytes per single RD/WR op. Instead of
> enabling the 511Bytes per RD/WR cycle on legacy platforms for no
> absolute ROIs, this change allows the max bytes per op upto 511Bytes
> from Gen9 onwards.
>
> v2:
> No Change.
> v3:
> Inline function for max_xfer_size and renaming of the macro.[Jani]
> v4:
> Extra brackets removed [ville]
> Commit msg is modified.
>
> Cc: Jani Nikula <jani.nik...@intel.com>
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Signed-off-by: Ramalingam C <ramalinga...@intel.com>
Reviewed-by: Jani Nikula <jani.nik...@intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_i2c.c | 11 +++++++++--
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index c08fd4ded688..df998c10c48e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3025,6 +3025,7 @@ enum i915_power_well_id {
> #define GMBUS_CYCLE_STOP (4<<25)
> #define GMBUS_BYTE_COUNT_SHIFT 16
> #define GMBUS_BYTE_COUNT_MAX 256U
> +#define GEN9_GMBUS_BYTE_COUNT_MAX 511U
> #define GMBUS_SLAVE_INDEX_SHIFT 8
> #define GMBUS_SLAVE_ADDR_SHIFT 1
> #define GMBUS_SLAVE_READ (1<<0)
> diff --git a/drivers/gpu/drm/i915/intel_i2c.c
> b/drivers/gpu/drm/i915/intel_i2c.c
> index e6875509bcd9..1c0f6b56b209 100644
> --- a/drivers/gpu/drm/i915/intel_i2c.c
> +++ b/drivers/gpu/drm/i915/intel_i2c.c
> @@ -361,6 +361,13 @@ 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,
> @@ -400,7 +407,7 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct
> i2c_msg *msg,
> int ret;
>
> do {
> - len = min(rx_size, GMBUS_BYTE_COUNT_MAX);
> + len = min(rx_size, gmbus_max_xfer_size(dev_priv));
>
> ret = gmbus_xfer_read_chunk(dev_priv, msg->addr,
> buf, len, gmbus1_index);
> @@ -462,7 +469,7 @@ 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);
--
Jani Nikula, Intel Open Source Technology Center
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