| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20171205173313.GX10981@intel.com>
Date: Tue, 5 Dec 2017 19:33:14 +0200
From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
To: Sean Paul <seanpaul@...omium.org>
Cc: dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
seanpaul@...gle.com, David Airlie <airlied@...ux.ie>,
linux-kernel@...r.kernel.org,
Rodrigo Vivi <rodrigo.vivi@...el.com>, daniel.vetter@...el.com
Subject: Re: [Intel-gfx] [PATCH v3 6/9] drm/i915: Make use of indexed write
GMBUS feature
On Tue, Dec 05, 2017 at 12:15:05AM -0500, Sean Paul wrote:
> This patch enables the indexed write feature of the GMBUS to concatenate
> 2 consecutive messages into one. The criteria for an indexed write is
> that both messages are writes, the first is length == 1, and the second
> is length > 0. The first message is sent out by the GMBUS as the slave
> command, and the second one is sent via the GMBUS FIFO as usual.
>
> Changes in v3:
> - Added to series
>
> Suggested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> Signed-off-by: Sean Paul <seanpaul@...omium.org>
> ---
> drivers/gpu/drm/i915/intel_i2c.c | 39 ++++++++++++++++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
> index 49fdf09f9919..7399009aee0a 100644
> --- a/drivers/gpu/drm/i915/intel_i2c.c
> +++ b/drivers/gpu/drm/i915/intel_i2c.c
> @@ -373,7 +373,8 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
>
> static int
> gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
> - unsigned short addr, u8 *buf, unsigned int len)
> + unsigned short addr, u8 *buf, unsigned int len,
> + u32 gmbus1_index)
> {
> unsigned int chunk_size = len;
> u32 val, loop;
> @@ -386,7 +387,7 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
>
> I915_WRITE_FW(GMBUS3, val);
> I915_WRITE_FW(GMBUS1,
> - GMBUS_CYCLE_WAIT |
> + gmbus1_index | GMBUS_CYCLE_WAIT |
> (chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
> (addr << GMBUS_SLAVE_ADDR_SHIFT) |
> GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
> @@ -409,7 +410,8 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
> }
>
> static int
> -gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
> +gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
> + u32 gmbus1_index)
> {
> u8 *buf = msg->buf;
> unsigned int tx_size = msg->len;
> @@ -419,7 +421,8 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
> do {
> len = min(tx_size, GMBUS_BYTE_COUNT_MAX);
>
> - ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len);
> + ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len,
> + gmbus1_index);
> if (ret)
> return ret;
>
> @@ -430,6 +433,14 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
> return 0;
> }
>
> +static int
> +gmbus_xfer_index_write(struct drm_i915_private *dev_priv, u8 cmd,
> + struct i2c_msg *msg)
> +{
> + u8 gmbus1_index = GMBUS_CYCLE_INDEX | (cmd << GMBUS_SLAVE_INDEX_SHIFT);
> + return gmbus_xfer_write(dev_priv, msg, gmbus1_index);
> +}
Instead of a duplicating the entire thing I'd just
- gmbus_xfer_index_read
+ gmbus_xfer_index
{
...
+ if (msgs[1].flags & I2C_M_RD)
gmbus_xfer_read()
+ else
+ gmbus_xfer_write()
...
}
Matches the current pattern better (no 'cmd' passed in), and
will give us the 2 byte index for free as well.
> +
> /*
> * The gmbus controller can combine a 1 or 2 byte write with a read that
> * immediately follows it by using an "INDEX" cycle.
> @@ -444,6 +455,20 @@ gmbus_is_index_read(struct i2c_msg *msgs, int i, int num)
> (msgs[i + 1].flags & I2C_M_RD));
> }
>
> +/*
> + * The gmbus controller can combine a 2-msg write into a single write that
> + * immediately follows it by using an "INDEX" cycle.
> + */
> +static bool
> +gmbus_is_index_write(struct i2c_msg *msgs, int i, int num)
> +{
> + return (i + 1 < num &&
> + msgs[i].addr == msgs[i + 1].addr &&
> + !(msgs[i].flags & I2C_M_RD) &&
> + !(msgs[i + 1].flags & I2C_M_RD) &&
> + (msgs[i].len == 1 || msgs[i + 1].len > 0));
Hmm. We don't have the len check for the second msg for reads. I wonder
if gmbus can actually do a zero length "read/write"?
> +}
> +
> static int
> gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
> {
> @@ -489,10 +514,14 @@ do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
> if (gmbus_is_index_read(msgs, i, num)) {
> ret = gmbus_xfer_index_read(dev_priv, &msgs[i]);
> inc = 2; /* an index read is two msgs */
> + } else if (gmbus_is_index_write(msgs, i, num)) {
> + ret = gmbus_xfer_index_write(dev_priv, msgs[i].buf[0],
> + &msgs[i + 1]);
> + inc = 2; /* an index write is two msgs */
> } else if (msgs[i].flags & I2C_M_RD) {
> ret = gmbus_xfer_read(dev_priv, &msgs[i], 0);
> } else {
> - ret = gmbus_xfer_write(dev_priv, &msgs[i]);
> + ret = gmbus_xfer_write(dev_priv, &msgs[i], 0);
> }
>
> if (!ret)
> --
> 2.15.0.531.g2ccb3012c9-goog
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ville Syrjälä
Intel OTC
Powered by blists - more mailing lists