| Message ID | 20200331183844.30488-1-ulf.hansson@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | amba/platform: Initialize dma_parms at the bus level | expand |
- Greg, Arnd, Linus, etc, On Tue, 31 Mar 2020 at 20:38, Ulf Hansson <ulf.hansson@linaro.org> wrote: > > It's currently the amba/platform driver's responsibility to initialize the > pointer, dma_parms, for its corresponding struct device. The benefit with this > approach allows us to avoid the initialization and to not waste memory for the > struct device_dma_parameters, as this can be decided on a case by case basis. > > However, it has turned out that this approach is not very practical. Not only > does it lead to open coding, but also to real errors. In principle callers of > dma_set_max_seg_size() doesn't check the error code, but just assumes it > succeeds. > > For these reasons, this series initializes the dma_parms from the amba/platform > bus at the device registration point. This also follows the way the PCI devices > are being managed, see pci_device_add(). > > If it turns out that this is an acceptable solution, we probably also want the > changes for stable, but I am not sure if it applies without conflicts. > > The series is based on v5.6. > > Kind regards > Ulf Hansson > > > Ulf Hansson (2): > driver core: platform: Initialize dma_parms for platform devices > amba: Initialize dma_parms for amba devices > > drivers/amba/bus.c | 1 + > drivers/base/platform.c | 2 ++ > include/linux/amba/bus.h | 1 + > include/linux/platform_device.h | 1 + > 4 files changed, 5 insertions(+) > > -- > 2.20.1 > Does this look okay or is there anything you would like me to change? Kind regards Uffe
It's currently the amba/platform driver's responsibility to initialize the pointer, dma_parms, for its corresponding struct device. The benefit with this approach allows us to avoid the initialization and to not waste memory for the struct device_dma_parameters, as this can be decided on a case by case basis. However, it has turned out that this approach is not very practical. Not only does it lead to open coding, but also to real errors. In principle callers of dma_set_max_seg_size() doesn't check the error code, but just assumes it succeeds. For these reasons, this series initializes the dma_parms from the amba/platform bus at the device registration point. This also follows the way the PCI devices are being managed, see pci_device_add(). If it turns out that this is an acceptable solution, we probably also want the changes for stable, but I am not sure if it applies without conflicts. The series is based on v5.6. Kind regards Ulf Hansson Ulf Hansson (2): driver core: platform: Initialize dma_parms for platform devices amba: Initialize dma_parms for amba devices drivers/amba/bus.c | 1 + drivers/base/platform.c | 2 ++ include/linux/amba/bus.h | 1 + include/linux/platform_device.h | 1 + 4 files changed, 5 insertions(+)