On 26/10/2022 05:44, Akhil R wrote:
On Thu, Oct 20, 2022 at 02:03:22PM +0530, Akhil R wrote:
Add support for dma-channel-mask so that only the specified channels
are used. This helps to reserve some channels for the firmware.
This was initially achieved by limiting the channel number to 31 in
the driver and adjusting the register address to skip channel0 which
was reserved for a firmware. Now, with this change, the driver can
align more to the actual hardware which has 32 channels.
Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>
---
drivers/dma/tegra186-gpc-dma.c | 37 +++++++++++++++++++++++++++-------
1 file changed, 30 insertions(+), 7 deletions(-)
diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-
dma.c
index fa9bda4a2bc6..1d1180db6d4e 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -161,7 +161,10 @@
#define TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT 5000 /* 5
msec */
/* Channel base address offset from GPCDMA base address */
-#define TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET 0x20000
+#define TEGRA_GPCDMA_CHANNEL_BASE_ADDR_OFFSET 0x10000
+
+/* Default channel mask reserving channel0 */
+#define TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK 0xfffffffe
struct tegra_dma;
struct tegra_dma_channel;
@@ -246,6 +249,7 @@ struct tegra_dma {
const struct tegra_dma_chip_data *chip_data;
unsigned long sid_m2d_reserved;
unsigned long sid_d2m_reserved;
+ u32 chan_mask;
void __iomem *base_addr;
struct device *dev;
struct dma_device dma_dev;
@@ -1288,7 +1292,7 @@ static struct dma_chan *tegra_dma_of_xlate(struct
of_phandle_args *dma_spec,
}
static const struct tegra_dma_chip_data tegra186_dma_chip_data = {
- .nr_channels = 31,
+ .nr_channels = 32,
This is an ABI break. A new kernel with an old DTB will use 32 channels
instead of 31. You should leave this and use the dma-channel-mask to
enable all 32 channels.
Hi Rob,
If using an old DTB, tdma->chan_mask will be default to 0xfffffffe since it
would not have the dma-channel-mask property. The driver would still
use 31 channels even if it uses an old DTB. Shouldn't it prevent the
ABI break?
Unfortunately no. Yes for an old DTB without the dma-channel-mask
property, we set the channel mask to 0xfffffffe, but this is not correct
because it only has 31 interrupts/channels and not 32. So I think we
will need to use of_irq_count() here.
Jon
--
nvpublic
