struct dma_channel {
        struct mutex dmalock;
-       char *device_id;
+       const char *device_id;
        enum dma_chan_status chan_status;
        struct dma_register *regs;
        struct dmasg *sg;               /* large mode descriptor */
 int dma_channel_active(unsigned int channel); /* check if a channel is in use */
 void disable_dma(unsigned int channel);
 void enable_dma(unsigned int channel);
-int request_dma(unsigned int channel, char *device_id);
+int request_dma(unsigned int channel, const char *device_id);
 int set_dma_callback(unsigned int channel, dma_interrupt_t callback,
                     void *data);
 void dma_disable_irq(unsigned int channel);
 
 /*------------------------------------------------------------------------------
  *     Request the specific DMA channel from the system.
  *-----------------------------------------------------------------------------*/
-int request_dma(unsigned int channel, char *device_id)
+int request_dma(unsigned int channel, const char *device_id)
 {
        pr_debug("request_dma() : BEGIN \n");