[PATCH v2] drm/dp/mst: Fix off-by-one typo when dump payload table

[PATCH v2] drm/dp/mst: Fix off-by-one typo when dump payload table

[Andy Shevchenko]

It seems there is a classical off-by-one typo from the beginning
when commit

  ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)")

introduced a new helper.

Fix a typo by introducing a macro constant.

Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
- use macro for buffer length on stack

 drivers/gpu/drm/drm_dp_mst_topology.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 6fac4129e6a2..658830620ca3 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2941,12 +2941,14 @@ static void drm_dp_mst_dump_mstb(struct seq_file *m,
 	}
 }
 
+#define DP_PAYLOAD_TABLE_SIZE		64
+
 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
 				  char *buf)
 {
 	int i;
 
-	for (i = 0; i < 64; i += 16) {
+	for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
 		if (drm_dp_dpcd_read(mgr->aux,
 				     DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
 				     &buf[i], 16) != 16)
@@ -3015,7 +3017,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 
 	mutex_lock(&mgr->lock);
 	if (mgr->mst_primary) {
-		u8 buf[64];
+		u8 buf[DP_PAYLOAD_TABLE_SIZE];
 		int ret;
 
 		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
@@ -3033,8 +3035,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 		seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
 			   buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
 		if (dump_dp_payload_table(mgr, buf))
-			seq_printf(m, "payload table: %*ph\n", 63, buf);
-
+			seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
 	}
 
 	mutex_unlock(&mgr->lock);
-- 
2.16.2

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Re: [PATCH v2] drm/dp/mst: Fix off-by-one typo when dump payload table

[Jani Nikula]

On Mon, 19 Mar 2018, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> It seems there is a classical off-by-one typo from the beginning
> when commit
>
>   ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)")
>
> introduced a new helper.
>
> Fix a typo by introducing a macro constant.
>
> Cc: Dave Airlie <airlied@redhat.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Pushed to drm-misc-next, thanks for the patch!

BR,
Jani.


> ---
> - use macro for buffer length on stack
>
>  drivers/gpu/drm/drm_dp_mst_topology.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 6fac4129e6a2..658830620ca3 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2941,12 +2941,14 @@ static void drm_dp_mst_dump_mstb(struct seq_file *m,
>  	}
>  }
>  
> +#define DP_PAYLOAD_TABLE_SIZE		64
> +
>  static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
>  				  char *buf)
>  {
>  	int i;
>  
> -	for (i = 0; i < 64; i += 16) {
> +	for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
>  		if (drm_dp_dpcd_read(mgr->aux,
>  				     DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
>  				     &buf[i], 16) != 16)
> @@ -3015,7 +3017,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  
>  	mutex_lock(&mgr->lock);
>  	if (mgr->mst_primary) {
> -		u8 buf[64];
> +		u8 buf[DP_PAYLOAD_TABLE_SIZE];
>  		int ret;
>  
>  		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
> @@ -3033,8 +3035,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  		seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
>  			   buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
>  		if (dump_dp_payload_table(mgr, buf))
> -			seq_printf(m, "payload table: %*ph\n", 63, buf);
> -
> +			seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
>  	}
>  
>  	mutex_unlock(&mgr->lock);

-- 
Jani Nikula, Intel Open Source Technology Center
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