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SubjectRe: [PATCH v2] drm/bridge: dw_hdmi: support i2c extended read mode
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Hi Nickey,


On 20-03-2017 02:57, 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://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.kernel.org_patch_7098101_&d=DwIBAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=yaVFU4TjGY0gVF8El1uKcisy6TPsyCl9uN7Wsis-qhY&m=cFlvlFSQCohfzkddQ6Jl6IlJ766epJ2Rsb329_KQEKo&s=4l-Ct5Bh-AZ0pzXWMJr64E8PVl56QkdSiHwxB3eHmz4&e= 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"
>
> 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>

Reviewed-by: Jose Abreu <joabreu@synopsys.com>

Best regards,
Jose Miguel Abreu

> ---
> 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;
> }

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