dma-debug: add kernel command line parameters

Impact: add dma_debug= and dma_debug_entries= kernel parameters

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

2 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 54f21a5c262b..0fa3c0545994 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -491,6 +491,16 @@ and is between 256 and 4096 characters. It is defined in the file
                         Range: 0 - 8192
                         Default: 64
 
+        dma_debug=off   If the kernel is compiled with DMA_API_DEBUG support
+                        this option disables the debugging code at boot.
+
+        dma_debug_entries=<number>
+                        This option allows to tune the number of preallocated
+                        entries for DMA-API debugging code. One entry is
+                        required per DMA-API allocation. Use this if the
+                        DMA-API debugging code disables itself because the
+                        architectural default is too low.
+
         hpet=           [X86-32,HPET] option to control HPET usage
                         Format: { enable (default) | disable | force }
                         disable: disable HPET and use PIT instead
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 5b50bb31f7c6..2ede46308024 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -64,6 +64,9 @@ static bool global_disable __read_mostly;
 static u32 num_free_entries;
 static u32 min_free_entries;
 
+/* number of preallocated entries requested by kernel cmdline */
+static u32 req_entries;
+
 /*
  * Hash related functions
  *
@@ -253,6 +256,9 @@ void dma_debug_init(u32 num_entries)
                 dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
         }
 
+        if (req_entries)
+                num_entries = req_entries;
+
         if (prealloc_memory(num_entries) != 0) {
                 printk(KERN_ERR "DMA-API: debugging out of memory error "
                                 "- disabled\n");
@@ -264,3 +270,35 @@ void dma_debug_init(u32 num_entries)
         printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
 }
 
+static __init int dma_debug_cmdline(char *str)
+{
+        if (!str)
+                return -EINVAL;
+
+        if (strncmp(str, "off", 3) == 0) {
+                printk(KERN_INFO "DMA-API: debugging disabled on kernel "
+                                 "command line\n");
+                global_disable = true;
+        }
+
+        return 0;
+}
+
+static __init int dma_debug_entries_cmdline(char *str)
+{
+        int res;
+
+        if (!str)
+                return -EINVAL;
+
+        res = get_option(&str, &req_entries);
+
+        if (!res)
+                req_entries = 0;
+
+        return 0;
+}
+
+__setup("dma_debug=", dma_debug_cmdline);
+__setup("dma_debug_entries=", dma_debug_entries_cmdline);
+