[PATCH 2/2] drm/dp: add DPCD/AUX logging
Imre Deak
imre.deak at intel.com
Thu Dec 22 08:54:53 UTC 2016
On Thu, 2016-12-22 at 08:02 +0100, Daniel Vetter wrote:
> On Wed, Dec 21, 2016 at 05:21:18PM -0500, Rob Clark wrote:
> > On Wed, Dec 21, 2016 at 3:41 PM, Imre Deak <imre.deak at intel.com> wrote:
> > > On Thu, 2016-02-25 at 16:15 -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()
> > > > v3: rename to more generic "AUX" instead of DP specific DPCD, add
> > > > DP_AUX_I2C_WRITE_STATUS_UPDATE
> > > >
> > > > Signed-off-by: Rob Clark <robdclark at gmail.com>
> > >
> > > I used the rebased version of this after Ville pointed me to it for
> > > remote debugging some odd adaptor behavior. It'd be quite useful imo, so:
> > > Acked-by: Imre Deak <imre.deak at intel.com>
> >
> > tbh I completely forgot about this patch.. mind posting the rebased
> > version (or push to a git tree somewhere)? IIRC there were just some
> > minor cosmetic things to fix up, probably worth doing that before I
> > forget about it again..
>
> There's patches for dynamic debugging floating around, I think that'd be
> the more interesting approach than adding ever more magic bits that no one
> understands. But besides that this makes sense.
Ok, although it's better than not having any way to debug and it could be
converted to dyndbg with the reset. For reference:
https://github.com/ideak/linux/commits/aux-debug
--Imre
> -Daniel
>
> >
> > BR,
> > -R
> >
> >
> > >
> > > > ---
> > > > drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
> > > > include/drm/drmP.h | 8 +++++-
> > > > 2 files changed, 58 insertions(+), 12 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> > > > index df64ed1..3ef35fd 100644
> > > > --- a/drivers/gpu/drm/drm_dp_helper.c
> > > > +++ b/drivers/gpu/drm/drm_dp_helper.c
> > > > @@ -160,6 +160,45 @@ 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_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
> > > > + msg->request, msg->address, msg->size);
> > > > +
> > > > + if (unlikely(drm_debug & DRM_UT_AUX)) {
> > > > + switch (msg->request & ~DP_AUX_I2C_MOT) {
> > > > + case DP_AUX_NATIVE_WRITE:
> > > > + case DP_AUX_I2C_WRITE:
> > > > + case DP_AUX_I2C_WRITE_STATUS_UPDATE:
> > > > + print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
> > > > + 16, 1, msg->buffer, msg->size, false);
> > > > + break;
> > > > + default:
> > > > + break;
> > > > + }
> > > > + }
> > > > +
> > > > + ret = aux->transfer(aux, msg);
> > > > +
> > > > + DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
> > > > +
> > > > + if (unlikely(drm_debug & DRM_UT_AUX) && (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 */
> > > >
> > > > /**
> > > > @@ -197,7 +236,7 @@ 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;
> > > > @@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
> > > > goto unlock;
> > > > }
> > > >
> > > > -
> > > > switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
> > > > case DP_AUX_NATIVE_REPLY_ACK:
> > > > if (err < size)
> > > > @@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
> > > > goto unlock;
> > > >
> > > > case DP_AUX_NATIVE_REPLY_NACK:
> > > > + DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
> > > > err = -EIO;
> > > > goto unlock;
> > > >
> > > > case DP_AUX_NATIVE_REPLY_DEFER:
> > > > + DRM_DEBUG_AUX("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:
> > > > @@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
> > > > int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
> > > >
> > > > 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_AUX("transaction failed: %d\n", ret);
> > > > return ret;
> > > > }
> > > >
> > > > @@ -568,11 +608,11 @@ 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_AUX("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_AUX("native defer\n");
> > > > /*
> > > > * We could check for I2C bit rate capabilities and if
> > > > * available adjust this interval. We could also be
> > > > @@ -601,12 +641,12 @@ 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_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
> > > > aux->i2c_nack_count++;
> > > > return -EREMOTEIO;
> > > >
> > > > case DP_AUX_I2C_REPLY_DEFER:
> > > > - DRM_DEBUG_KMS("I2C defer\n");
> > > > + DRM_DEBUG_AUX("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
> > > > @@ -625,7 +665,7 @@ 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;
> > > > }
> > > >
> > > > @@ -653,7 +693,7 @@ 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_AUX("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 3c8422c..cc524b5 100644
> > > > --- a/include/drm/drmP.h
> > > > +++ b/include/drm/drmP.h
> > > > @@ -117,7 +117,7 @@ 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 +129,7 @@ struct dma_buf_attachment;
> > > > #define DRM_UT_PRIME 0x08
> > > > #define DRM_UT_ATOMIC 0x10
> > > > #define DRM_UT_VBL 0x20
> > > > +#define DRM_UT_AUX 0x40
> > > >
> > > > extern __printf(2, 3)
> > > > void drm_ut_debug_printk(const char *function_name,
> > > > @@ -226,6 +227,11 @@ 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_AUX(fmt, args...) \
> > > > + do { \
> > > > + if (unlikely(drm_debug & DRM_UT_AUX)) \
> > > > + drm_ut_debug_printk(__func__, fmt, ##args); \
> > > > + } while (0)
> > > >
> > > > /*@}*/
> > > >
> >
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