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    SubjectRe: [PATCH v2] drm/bridge: dw_hdmi: support i2c extended read mode
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    On 03/20/2017 08:27 AM, Nickey Yang wrote:
    > "I2C Master Interface Extended Read Mode" implements a segment
    > pointer-based read operation using the Special Register configuration.
    >
    > This patch fix https://patchwork.kernel.org/patch/7098101/ mentioned
    > "The current implementation does not support "I2C Master Interface
    > Extended Read Mode" to read data addressed by non-zero segment
    > pointer, this means that if EDID has more than 1 extension blocks"

    Queued to drm-misc-next after fixing up commit message.

    Archit

    >
    > With this patch,dw-hdmi can read EDID data with 1/2/4 blocks.
    >
    > Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
    > Reviewed-by: Douglas Anderson <dianders@chromium.org>
    > ---
    > drivers/gpu/drm/bridge/dw-hdmi.c | 38 ++++++++++++++++++++++++--------------
    > 1 file changed, 24 insertions(+), 14 deletions(-)
    >
    > diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
    > index 9a9ec27..3b93655 100644
    > --- a/drivers/gpu/drm/bridge/dw-hdmi.c
    > +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
    > @@ -32,6 +32,7 @@
    > #include "dw-hdmi.h"
    > #include "dw-hdmi-audio.h"
    >
    > +#define DDC_SEGMENT_ADDR 0x30
    > #define HDMI_EDID_LEN 512
    >
    > #define RGB 0
    > @@ -111,6 +112,7 @@ struct dw_hdmi_i2c {
    >
    > u8 slave_reg;
    > bool is_regaddr;
    > + bool is_segment;
    > };
    >
    > struct dw_hdmi_phy_data {
    > @@ -258,8 +260,12 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
    > reinit_completion(&i2c->cmp);
    >
    > hdmi_writeb(hdmi, i2c->slave_reg++, HDMI_I2CM_ADDRESS);
    > - hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
    > - HDMI_I2CM_OPERATION);
    > + if (i2c->is_segment)
    > + hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ_EXT,
    > + HDMI_I2CM_OPERATION);
    > + else
    > + hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
    > + HDMI_I2CM_OPERATION);
    >
    > stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10);
    > if (!stat)
    > @@ -271,6 +277,7 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
    >
    > *buf++ = hdmi_readb(hdmi, HDMI_I2CM_DATAI);
    > }
    > + i2c->is_segment = false;
    >
    > return 0;
    > }
    > @@ -320,12 +327,6 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
    > dev_dbg(hdmi->dev, "xfer: num: %d, addr: %#x\n", num, addr);
    >
    > for (i = 0; i < num; i++) {
    > - if (msgs[i].addr != addr) {
    > - dev_warn(hdmi->dev,
    > - "unsupported transfer, changed slave address\n");
    > - return -EOPNOTSUPP;
    > - }
    > -
    > if (msgs[i].len == 0) {
    > dev_dbg(hdmi->dev,
    > "unsupported transfer %d/%d, no data\n",
    > @@ -345,15 +346,24 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
    > /* Set slave device register address on transfer */
    > i2c->is_regaddr = false;
    >
    > + /* Set segment pointer for I2C extended read mode operation */
    > + i2c->is_segment = false;
    > +
    > for (i = 0; i < num; i++) {
    > dev_dbg(hdmi->dev, "xfer: num: %d/%d, len: %d, flags: %#x\n",
    > i + 1, num, msgs[i].len, msgs[i].flags);
    > -
    > - if (msgs[i].flags & I2C_M_RD)
    > - ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf, msgs[i].len);
    > - else
    > - ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf, msgs[i].len);
    > -
    > + if (msgs[i].addr == DDC_SEGMENT_ADDR && msgs[i].len == 1) {
    > + i2c->is_segment = true;
    > + hdmi_writeb(hdmi, DDC_SEGMENT_ADDR, HDMI_I2CM_SEGADDR);
    > + hdmi_writeb(hdmi, *msgs[i].buf, HDMI_I2CM_SEGPTR);
    > + } else {
    > + if (msgs[i].flags & I2C_M_RD)
    > + ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf,
    > + msgs[i].len);
    > + else
    > + ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf,
    > + msgs[i].len);
    > + }
    > if (ret < 0)
    > break;
    > }
    >

    --
    Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
    a Linux Foundation Collaborative Project

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