diff options
Diffstat (limited to 'drivers/media/pci/tw686x/tw686x-core.c')
| -rw-r--r-- | drivers/media/pci/tw686x/tw686x-core.c | 56 |
1 files changed, 48 insertions, 8 deletions
diff --git a/drivers/media/pci/tw686x/tw686x-core.c b/drivers/media/pci/tw686x/tw686x-core.c index cf53b0e97be2..71a0453b1af1 100644 --- a/drivers/media/pci/tw686x/tw686x-core.c +++ b/drivers/media/pci/tw686x/tw686x-core.c @@ -21,12 +21,14 @@ * under stress testings it has been found that the machine can * freeze completely if DMA registers are programmed while streaming * is active. - * This driver tries to access hardware registers as infrequently - * as possible by: - * i. allocating fixed DMA buffers and memcpy'ing into - * vmalloc'ed buffers - * ii. using a timer to mitigate the rate of DMA reset operations, - * on DMA channels error. + * + * Therefore, driver implements a dma_mode called 'memcpy' which + * avoids cycling the DMA buffers, and insteads allocates extra DMA buffers + * and then copies into vmalloc'ed user buffers. + * + * In addition to this, when streaming is on, the driver tries to access + * hardware registers as infrequently as possible. This is done by using + * a timer to limit the rate at which DMA is reset on DMA channels error. */ #include <linux/init.h> @@ -55,6 +57,42 @@ static u32 dma_interval = 0x00098968; module_param(dma_interval, int, 0444); MODULE_PARM_DESC(dma_interval, "Minimum time span for DMA interrupting host"); +static unsigned int dma_mode = TW686X_DMA_MODE_MEMCPY; +static const char *dma_mode_name(unsigned int mode) +{ + switch (mode) { + case TW686X_DMA_MODE_MEMCPY: + return "memcpy"; + case TW686X_DMA_MODE_CONTIG: + return "contig"; + case TW686X_DMA_MODE_SG: + return "sg"; + default: + return "unknown"; + } +} + +static int tw686x_dma_mode_get(char *buffer, struct kernel_param *kp) +{ + return sprintf(buffer, dma_mode_name(dma_mode)); +} + +static int tw686x_dma_mode_set(const char *val, struct kernel_param *kp) +{ + if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_MEMCPY))) + dma_mode = TW686X_DMA_MODE_MEMCPY; + else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_CONTIG))) + dma_mode = TW686X_DMA_MODE_CONTIG; + else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_SG))) + dma_mode = TW686X_DMA_MODE_SG; + else + return -EINVAL; + return 0; +} +module_param_call(dma_mode, tw686x_dma_mode_set, tw686x_dma_mode_get, + &dma_mode, S_IRUGO|S_IWUSR); +MODULE_PARM_DESC(dma_mode, "DMA operation mode (memcpy/contig/sg, default=memcpy)"); + void tw686x_disable_channel(struct tw686x_dev *dev, unsigned int channel) { u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE); @@ -212,6 +250,7 @@ static int tw686x_probe(struct pci_dev *pci_dev, if (!dev) return -ENOMEM; dev->type = pci_id->driver_data; + dev->dma_mode = dma_mode; sprintf(dev->name, "tw%04X", pci_dev->device); dev->video_channels = kcalloc(max_channels(dev), @@ -228,9 +267,10 @@ static int tw686x_probe(struct pci_dev *pci_dev, goto free_video; } - pr_info("%s: PCI %s, IRQ %d, MMIO 0x%lx\n", dev->name, + pr_info("%s: PCI %s, IRQ %d, MMIO 0x%lx (%s mode)\n", dev->name, pci_name(pci_dev), pci_dev->irq, - (unsigned long)pci_resource_start(pci_dev, 0)); + (unsigned long)pci_resource_start(pci_dev, 0), + dma_mode_name(dma_mode)); dev->pci_dev = pci_dev; if (pci_enable_device(pci_dev)) { |