[PATCH libdrm] amdgpu: dynamically detect number of drm devices

[xiyuan]

Hi Christian,

The problem I encountered is that amdgpu_test throws segment fault on a 
platform with 1 iGPU + 4 dGPU. The root cause is that 'drm_count' 
returned by drmGetDevices() is 5 which exceeds MAX_CARDS_SUPPORTED, so I 
decided to make it more flexible to get the actual number of drm devices.

Setting MAX_CARDS_SUPPORTED to 128 is fine to solve my problem but is it 
a bit large for traversal?

Regards,
Xiaojie


On 04/19/2018 07:06 PM, Christian König wrote:
> Wouldn't it be simpler to just set MAX_CARDS_SUPPORTED to 128?
>
> Regards,
> Christian.
>
> Am 19.04.2018 um 12:12 schrieb Xiaojie Yuan:
>> Change-Id: I36764951bebbcbf06cf84dd43ee946a34ec7b100
>> Signed-off-by: Xiaojie Yuan <Xiaojie.Yuan at amd.com>
>> ---
>>   tests/amdgpu/amdgpu_test.c | 44 ++++++++++++++++++++++++++++----------
>>   tests/amdgpu/amdgpu_test.h |  7 +-----
>>   2 files changed, 34 insertions(+), 17 deletions(-)
>>
>> diff --git a/tests/amdgpu/amdgpu_test.c b/tests/amdgpu/amdgpu_test.c
>> index 96fcd687..f7ac4ab4 100644
>> --- a/tests/amdgpu/amdgpu_test.c
>> +++ b/tests/amdgpu/amdgpu_test.c
>> @@ -61,7 +61,8 @@
>>    *  Open handles for amdgpu devices
>>    *
>>    */
>> -int drm_amdgpu[MAX_CARDS_SUPPORTED];
>> +int *drm_amdgpu;
>> +size_t num_drm_devices;
>>     /** Open render node to test */
>>   int open_render_node = 0;    /* By default run most tests on 
>> primary node */
>> @@ -238,16 +239,16 @@ static const char options[]   = "hlrps:t:b:d:f";
>>    */
>>   static int amdgpu_open_devices(int open_render_node)
>>   {
>> -    drmDevicePtr devices[MAX_CARDS_SUPPORTED];
>> +    drmDevicePtr *devices;
>>       int i;
>>       int drm_node;
>>       int amd_index = 0;
>>       int drm_count;
>> +    int drm_count2;
>>       int fd;
>>       drmVersionPtr version;
>>   -    drm_count = drmGetDevices2(0, devices, MAX_CARDS_SUPPORTED);
>> -
>> +    drm_count = drmGetDevices2(0, NULL, 0);
>>       if (drm_count < 0) {
>>           fprintf(stderr,
>>               "drmGetDevices2() returned an error %d\n",
>> @@ -255,6 +256,27 @@ static int amdgpu_open_devices(int 
>> open_render_node)
>>           return 0;
>>       }
>>   +    devices = calloc(drm_count, sizeof(drmDevicePtr));
>> +    if (!devices) {
>> +        goto end;
>> +    }
>> +
>> +    drm_amdgpu = calloc(drm_count, sizeof(int));
>> +    if (!drm_amdgpu) {
>> +        goto end;
>> +    }
>> +
>> +    for (i = 0; i < drm_count; i++)
>> +        drm_amdgpu[i] = -1;
>> +
>> +    drm_count2 = drmGetDevices2(0, devices, drm_count);
>> +    if (drm_count2 != drm_count) {
>> +        fprintf(stderr, "number of drm devices changed");
>> +        goto end;
>> +    }
>> +
>> +    num_drm_devices = drm_count;
>> +
>>       for (i = 0; i < drm_count; i++) {
>>           /* If this is not PCI device, skip*/
>>           if (devices[i]->bustype != DRM_BUS_PCI)
>> @@ -302,7 +324,9 @@ static int amdgpu_open_devices(int open_render_node)
>>           amd_index++;
>>       }
>>   +end:
>>       drmFreeDevices(devices, drm_count);
>> +    free(devices);
>>       return amd_index;
>>   }
>>   @@ -311,9 +335,11 @@ static int amdgpu_open_devices(int 
>> open_render_node)
>>   static void amdgpu_close_devices()
>>   {
>>       int i;
>> -    for (i = 0; i < MAX_CARDS_SUPPORTED; i++)
>> +    for (i = 0; i < num_drm_devices; i++)
>>           if (drm_amdgpu[i] >=0)
>>               close(drm_amdgpu[i]);
>> +
>> +    free(drm_amdgpu);
>>   }
>>     /* Print AMD devices information */
>> @@ -339,7 +365,7 @@ static void amdgpu_print_devices()
>>         /* Display information of AMD devices */
>>       printf("Devices:\n");
>> -    for (i = 0; i < MAX_CARDS_SUPPORTED && drm_amdgpu[i] >=0; i++)
>> +    for (i = 0; i < num_drm_devices && drm_amdgpu[i] >=0; i++)
>>           if (drmGetDevice2(drm_amdgpu[i],
>>               DRM_DEVICE_GET_PCI_REVISION,
>>               &device) == 0) {
>> @@ -377,7 +403,7 @@ static int amdgpu_find_device(uint8_t bus, 
>> uint16_t dev)
>>       int i;
>>       drmDevicePtr device;
>>   -    for (i = 0; i < MAX_CARDS_SUPPORTED && drm_amdgpu[i] >= 0; i++) {
>> +    for (i = 0; i < num_drm_devices && drm_amdgpu[i] >= 0; i++) {
>>           if (drmGetDevice2(drm_amdgpu[i],
>>               DRM_DEVICE_GET_PCI_REVISION,
>>               &device) == 0) {
>> @@ -456,10 +482,6 @@ int main(int argc, char **argv)
>>       int display_list = 0;
>>       int force_run = 0;
>>   -    for (i = 0; i < MAX_CARDS_SUPPORTED; i++)
>> -        drm_amdgpu[i] = -1;
>> -
>> -
>>       /* Parse command line string */
>>       opterr = 0;        /* Do not print error messages from getopt */
>>       while ((c = getopt(argc, argv, options)) != -1) {
>> diff --git a/tests/amdgpu/amdgpu_test.h b/tests/amdgpu/amdgpu_test.h
>> index 62875736..8a604fe4 100644
>> --- a/tests/amdgpu/amdgpu_test.h
>> +++ b/tests/amdgpu/amdgpu_test.h
>> @@ -27,13 +27,8 @@
>>   #include "amdgpu.h"
>>   #include "amdgpu_drm.h"
>>   -/**
>> - * Define max. number of card in system which we are able to handle
>> - */
>> -#define MAX_CARDS_SUPPORTED     4
>> -
>>   /* Forward reference for array to keep "drm" handles */
>> -extern int drm_amdgpu[MAX_CARDS_SUPPORTED];
>> +extern int *drm_amdgpu;
>>     /* Global variables */
>>   extern int open_render_node;
>