[PATCH 2/2] drm/dp: add DPCD logging
Ville Syrjälä
ville.syrjala at linux.intel.com
Fri Dec 11 08:41:25 PST 2015
On Wed, Dec 09, 2015 at 04:20:10PM -0500, Rob Clark wrote:
> Add a new drm_debug bit for turning on DPCD logging, to aid debugging
> with troublesome monitors.
>
> v2: don't try to hexdump the universe if driver returns -errno, and
> change the "too many retries" traces to DRM_ERROR()
>
> Signed-off-by: Rob Clark <robdclark at gmail.com>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 60 ++++++++++++++++++++++++++++++++++-------
> include/drm/drmP.h | 10 ++++++-
> 2 files changed, 59 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 76e08dc..3f27cc9 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -159,6 +159,44 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
> }
> EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
>
> +static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> +{
> + ssize_t ret;
> +
> + DRM_DEBUG_DPCD("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
> + msg->request, msg->address, msg->size);
> +
> + if (unlikely(drm_debug & DRM_UT_DPCD)) {
> + switch (msg->request & ~DP_AUX_I2C_MOT) {
> + case DP_AUX_NATIVE_WRITE:
> + case DP_AUX_I2C_WRITE:
Missing DP_AUX_I2C_WRITE_STATUS_UPDATE on purpose?
> + print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
> + 16, 1, msg->buffer, msg->size, false);
i2c != dpcd
So might be it should be called DRM_UT_AUX etc.
> + break;
> + default:
> + break;
> + }
> + }
> +
> + ret = aux->transfer(aux, msg);
> +
> + DRM_DEBUG_DPCD("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
I was thinking the reply might contain random garbage on error, but at
least we memset the whole thing to zero initially, so I guess it ought
to be good enough.
> +
> + if (unlikely(drm_debug & DRM_UT_DPCD) && (ret > 0)) {
> + switch (msg->request & ~DP_AUX_I2C_MOT) {
> + case DP_AUX_NATIVE_READ:
> + case DP_AUX_I2C_READ:
> + print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
> + 16, 1, msg->buffer, ret, false);
> + break;
> + default:
> + break;
> + }
> + }
> +
> + return ret;
> +}
> +
> #define AUX_RETRY_INTERVAL 500 /* us */
>
> /**
> @@ -196,7 +234,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
> */
> for (retry = 0; retry < 32; retry++) {
>
> - err = aux->transfer(aux, &msg);
> + err = aux_transfer(aux, &msg);
> if (err < 0) {
> if (err == -EBUSY)
> continue;
> @@ -212,16 +250,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
> goto unlock;
>
> case DP_AUX_NATIVE_REPLY_NACK:
> + DRM_DEBUG_DPCD("native nack (result=%d, size=%zu)\n", err, msg.size);
> err = -EIO;
> goto unlock;
>
> case DP_AUX_NATIVE_REPLY_DEFER:
> + DRM_DEBUG_DPCD("native defer\n");
> usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
> break;
> }
> }
>
> - DRM_DEBUG_KMS("too many retries, giving up\n");
> + DRM_ERROR("DPCD: too many retries, giving up!\n");
> err = -EIO;
>
> unlock:
> @@ -550,12 +590,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> WARN_ON(!mutex_is_locked(&aux->hw_mutex));
>
> for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
> - ret = aux->transfer(aux, msg);
> + ret = aux_transfer(aux, msg);
> if (ret < 0) {
> if (ret == -EBUSY)
> continue;
>
> - DRM_DEBUG_KMS("transaction failed: %d\n", ret);
> + DRM_DEBUG_DPCD("transaction failed: %d\n", ret);
> return ret;
> }
>
> @@ -569,11 +609,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> break;
>
> case DP_AUX_NATIVE_REPLY_NACK:
> - DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
> + DRM_DEBUG_DPCD("native nack (result=%d, size=%zu)\n", ret, msg->size);
> return -EREMOTEIO;
>
> case DP_AUX_NATIVE_REPLY_DEFER:
> - DRM_DEBUG_KMS("native defer\n");
> + DRM_DEBUG_DPCD("native defer\n");
> /*
> * We could check for I2C bit rate capabilities and if
> * available adjust this interval. We could also be
> @@ -602,12 +642,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> return ret;
>
> case DP_AUX_I2C_REPLY_NACK:
> - DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
> + DRM_DEBUG_DPCD("I2C nack (result=%d, size=%zu\n", ret, msg->size);
^
Might as well add the missing parenthesis while touching this.
And yes, it was me who messed it up originally.
> aux->i2c_nack_count++;
> return -EREMOTEIO;
>
> case DP_AUX_I2C_REPLY_DEFER:
> - DRM_DEBUG_KMS("I2C defer\n");
> + DRM_DEBUG_DPCD("I2C defer\n");
> /* DP Compliance Test 4.2.2.5 Requirement:
> * Must have at least 7 retries for I2C defers on the
> * transaction to pass this test
> @@ -626,7 +666,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> }
> }
>
> - DRM_DEBUG_KMS("too many retries, giving up\n");
> + DRM_ERROR("I2C: too many retries, giving up\n");
> return -EREMOTEIO;
> }
>
> @@ -654,7 +694,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
> return err == 0 ? -EPROTO : err;
>
> if (err < msg.size && err < ret) {
> - DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
> + DRM_DEBUG_DPCD("Partial I2C reply: requested %zu bytes got %d bytes\n",
> msg.size, err);
> ret = err;
> }
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index 0a271ca..ac4d622 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -110,6 +110,8 @@ struct dma_buf_attachment;
> * VBL: used for verbose debug message in the vblank code
> * This is the category used by the DRM_DEBUG_VBL() macro.
> *
> + * DPCD: used to log (displayport) DPCD messages
> + *
> * Enabling verbose debug messages is done through the drm.debug parameter,
> * each category being enabled by a bit.
> *
> @@ -117,7 +119,7 @@ struct dma_buf_attachment;
> * drm.debug=0x2 will enable DRIVER messages
> * drm.debug=0x3 will enable CORE and DRIVER messages
> * ...
> - * drm.debug=0x3f will enable all messages
> + * drm.debug=0x7f will enable all messages
> *
> * An interesting feature is that it's possible to enable verbose logging at
> * run-time by echoing the debug value in its sysfs node:
> @@ -129,6 +131,7 @@ struct dma_buf_attachment;
> #define DRM_UT_PRIME 0x08
> #define DRM_UT_ATOMIC 0x10
> #define DRM_UT_VBL 0x20
> +#define DRM_UT_DPCD 0x40
>
> extern __printf(2, 3)
> void drm_ut_debug_printk(const char *function_name,
> @@ -226,6 +229,11 @@ void drm_err(const char *format, ...);
> if (unlikely(drm_debug & DRM_UT_VBL)) \
> drm_ut_debug_printk(__func__, fmt, ##args); \
> } while (0)
> +#define DRM_DEBUG_DPCD(fmt, args...) \
> + do { \
> + if (unlikely(drm_debug & DRM_UT_DPCD)) \
> + drm_ut_debug_printk(__func__, fmt, ##args); \
> + } while (0)
>
> /*@}*/
>
> --
> 2.5.0
>
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--
Ville Syrjälä
Intel OTC
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