DMA from Local memory to PCI device - DMA Address
I am working on a driver that uses PCI DMA transfers from processor local memory (slave memory) to the PCI device. The board that is use is MIPS based & the kernel version is linux 2.6.18.8. For some reason, i am not able to achieve this. Instead, if i use __get_free_pages which allocates pages from main memory, the dma transfer happens. Given below are the steps i followed for each case
Case 1 : (using get_free_pages)
a. allocate memory
__get_free_pages() ---> returns virtual address
b. assign the physical address to dma_handle
*dma_handle = __pa(ret)
c. Return the uncach address to the callee
return UNCAC_ADDR(ret);
With the above steps dma happen and the system works as expected.
Now, in the next case, i replace step a with my custom function which allocates memory from the system local memory (slave memory). All other steps are kept as is.
Case 2 :
a. allocate memory from slave memory
custom_allocate_memory () ---> returns physical address of the slave memory
__va( custom_allocate_memory () ) ---> this will convert the physical address to virtual memory. This is done so as to keep the step b & step c of Case 1 as it is.
b. assign the physical address to dma_handle
*dma_handle = __pa(ret)
c. Return the uncached address to the callee
return UNCAC_ADDR(ret);
In Case2, the DMA doesn't work and returns an error which indicates that the address provided to the DMA is wrong? What could be the probable mistake i am doing here? Is there anything else to be considered while replacing the __get_free_pages() with my custom function?
Can someone give me a pointer of how Case 2 can be acheived?
-Joe
Categories
- All Categories
- 230 LFX Mentorship
- 230 LFX Mentorship: Linux Kernel
- 812 Linux Foundation IT Professional Programs
- 365 Cloud Engineer IT Professional Program
- 183 Advanced Cloud Engineer IT Professional Program
- 82 DevOps Engineer IT Professional Program
- 151 Cloud Native Developer IT Professional Program
- 138 Express Training Courses & Microlearning
- 138 Express Courses - Discussion Forum
- Microlearning - Discussion Forum
- 6.4K Training Courses
- 48 LFC110 Class Forum - Discontinued
- 71 LFC131 Class Forum
- 44 LFD102 Class Forum
- 228 LFD103 Class Forum
- 19 LFD110 Class Forum
- 42 LFD121 Class Forum
- 18 LFD133 Class Forum
- 8 LFD134 Class Forum
- 18 LFD137 Class Forum
- 71 LFD201 Class Forum
- 5 LFD210 Class Forum
- 5 LFD210-CN Class Forum
- 2 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum - Discontinued
- 2 LFD233 Class Forum
- 4 LFD237 Class Forum
- 24 LFD254 Class Forum
- 701 LFD259 Class Forum
- 111 LFD272 Class Forum - Discontinued
- 4 LFD272-JP クラス フォーラム
- 13 LFD273 Class Forum
- 180 LFS101 Class Forum
- 1 LFS111 Class Forum
- 3 LFS112 Class Forum
- 3 LFS116 Class Forum
- 7 LFS118 Class Forum
- LFS120 Class Forum
- 9 LFS142 Class Forum
- 8 LFS144 Class Forum
- 4 LFS145 Class Forum
- 3 LFS146 Class Forum
- 2 LFS148 Class Forum
- 15 LFS151 Class Forum
- 4 LFS157 Class Forum
- 44 LFS158 Class Forum
- LFS158-JP クラス フォーラム
- 10 LFS162 Class Forum
- 2 LFS166 Class Forum
- 4 LFS167 Class Forum
- 3 LFS170 Class Forum
- 2 LFS171 Class Forum
- 3 LFS178 Class Forum
- 3 LFS180 Class Forum
- 2 LFS182 Class Forum
- 5 LFS183 Class Forum
- 32 LFS200 Class Forum
- 737 LFS201 Class Forum - Discontinued
- 3 LFS201-JP クラス フォーラム - Discontinued
- 19 LFS203 Class Forum
- 135 LFS207 Class Forum
- 2 LFS207-DE-Klassenforum
- 1 LFS207-JP クラス フォーラム
- 302 LFS211 Class Forum
- 56 LFS216 Class Forum
- 52 LFS241 Class Forum
- 48 LFS242 Class Forum
- 38 LFS243 Class Forum
- 15 LFS244 Class Forum
- 5 LFS245 Class Forum
- LFS246 Class Forum
- LFS248 Class Forum
- 52 LFS250 Class Forum
- 2 LFS250-JP クラス フォーラム
- 1 LFS251 Class Forum
- 156 LFS253 Class Forum
- 1 LFS254 Class Forum
- 1 LFS255 Class Forum
- 9 LFS256 Class Forum
- 1 LFS257 Class Forum
- 1.3K LFS258 Class Forum
- 10 LFS258-JP クラス フォーラム
- 129 LFS260 Class Forum
- 160 LFS261 Class Forum
- 43 LFS262 Class Forum
- 82 LFS263 Class Forum - Discontinued
- 15 LFS264 Class Forum - Discontinued
- 11 LFS266 Class Forum - Discontinued
- 24 LFS267 Class Forum
- 25 LFS268 Class Forum
- 32 LFS269 Class Forum
- 6 LFS270 Class Forum
- 202 LFS272 Class Forum - Discontinued
- 2 LFS272-JP クラス フォーラム
- 4 LFS147 Class Forum
- 1 LFS274 Class Forum
- 4 LFS281 Class Forum
- 12 LFW111 Class Forum
- 262 LFW211 Class Forum
- 184 LFW212 Class Forum
- 15 SKF100 Class Forum
- 1 SKF200 Class Forum
- 1 SKF201 Class Forum
- 797 Hardware
- 199 Drivers
- 68 I/O Devices
- 37 Monitors
- 104 Multimedia
- 174 Networking
- 91 Printers & Scanners
- 85 Storage
- 759 Linux Distributions
- 82 Debian
- 67 Fedora
- 17 Linux Mint
- 13 Mageia
- 23 openSUSE
- 148 Red Hat Enterprise
- 31 Slackware
- 13 SUSE Enterprise
- 354 Ubuntu
- 470 Linux System Administration
- 39 Cloud Computing
- 71 Command Line/Scripting
- Github systems admin projects
- 95 Linux Security
- 78 Network Management
- 102 System Management
- 47 Web Management
- 69 Mobile Computing
- 18 Android
- 38 Development
- 1.2K New to Linux
- 1K Getting Started with Linux
- 374 Off Topic
- 115 Introductions
- 174 Small Talk
- 24 Study Material
- 807 Programming and Development
- 304 Kernel Development
- 485 Software Development
- 1.8K Software
- 263 Applications
- 183 Command Line
- 3 Compiling/Installing
- 987 Games
- 317 Installation
- 102 All In Program
- 102 All In Forum
Upcoming Training
-
August 20, 2018
Kubernetes Administration (LFS458)
-
August 20, 2018
Linux System Administration (LFS301)
-
August 27, 2018
Open Source Virtualization (LFS462)
-
August 27, 2018
Linux Kernel Debugging and Security (LFD440)