Re: [PATCH V2 7/8] i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()

On 28/07/2026 23:10, Frank Li wrote:
> On Tue, Jul 28, 2026 at 06:53:07PM +0300, Adrian Hunter wrote:
>> The MIPI I3C HCI driver needs to identify the underlying system device
>> used for DMA mapping and PM operations. The logic for determining that
>> device is currently embedded in the DMA implementation.
>>
>> Factor this code out into i3c_hci_sysdev() so it can be shared by other
>> parts of the driver and keep the device-selection logic in one place.
>>
>> Signed-off-by: Adrian Hunter <[email protected]>
>> ---
>>
>>
>> Changes in V2:
>>
>> 	None
>>
>>
>>  drivers/i3c/master/mipi-i3c-hci/core.c | 12 ++++++++++++
>>  drivers/i3c/master/mipi-i3c-hci/dma.c  | 15 +--------------
>>  drivers/i3c/master/mipi-i3c-hci/hci.h  |  2 ++
>>  3 files changed, 15 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
>> index cfe9b5390b56..0212c9e984cf 100644
>> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
>> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
>> @@ -15,6 +15,7 @@
>>  #include <linux/interrupt.h>
>>  #include <linux/iopoll.h>
>>  #include <linux/module.h>
>> +#include <linux/pci.h>
>>  #include <linux/platform_data/mipi-i3c-hci.h>
>>  #include <linux/platform_device.h>
>>  #include <linux/pm_runtime.h>
>> @@ -117,6 +118,17 @@ static inline struct i3c_hci *to_i3c_hci(struct i3c_master_controller *m)
>>  	return container_of(m, struct i3c_hci, master);
>>  }
>>
>> +/*
>> + * Determine the device that does PM / DMA and has IOMMU setup done for it in
>> + * case of enabled IOMMU (for use with the DMA API).
>> + * Such device is either "mipi-i3c-hci" platform device (OF/ACPI enumeration)
>> + * parent or grandparent (PCI enumeration).
>> + */
>> +struct device *i3c_hci_sysdev(struct device *dev)
> 
> Is it simpler if argument is struct i3c_hci *hci

It will be called before hci->master.dev.parent is populated,
see patch 8.

> 
> Frank
> 
>> +{
>> +	return dev->parent && dev_is_pci(dev->parent) ? dev->parent : dev;
>> +}
>> +
>>  static void i3c_hci_set_master_dyn_addr(struct i3c_hci *hci)
>>  {
>>  	reg_write(MASTER_DEVICE_ADDR,
>> diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
>> index 0672ed1132f8..7c2b20474130 100644
>> --- a/drivers/i3c/master/mipi-i3c-hci/dma.c
>> +++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
>> @@ -15,7 +15,6 @@
>>  #include <linux/errno.h>
>>  #include <linux/i3c/master.h>
>>  #include <linux/io.h>
>> -#include <linux/pci.h>
>>
>>  #include "hci.h"
>>  #include "cmd.h"
>> @@ -301,23 +300,11 @@ static int hci_dma_init(struct i3c_hci *hci)
>>  {
>>  	struct hci_rings_data *rings;
>>  	struct hci_rh_data *rh;
>> -	struct device *sysdev;
>>  	u32 regval;
>>  	unsigned int i, nr_rings, xfers_sz, resps_sz;
>>  	unsigned int ibi_status_ring_sz, ibi_data_ring_sz;
>>  	int ret;
>>
>> -	/*
>> -	 * Set pointer to a physical device that does DMA and has IOMMU setup
>> -	 * done for it in case of enabled IOMMU and use it with the DMA API.
>> -	 * Here such device is either
>> -	 * "mipi-i3c-hci" platform device (OF/ACPI enumeration) parent or
>> -	 * grandparent (PCI enumeration).
>> -	 */
>> -	sysdev = hci->master.dev.parent;
>> -	if (sysdev->parent && dev_is_pci(sysdev->parent))
>> -		sysdev = sysdev->parent;
>> -
>>  	regval = rhs_reg_read(CONTROL);
>>  	nr_rings = FIELD_GET(MAX_HEADER_COUNT_CAP, regval);
>>  	dev_dbg(&hci->master.dev, "%d DMA rings available\n", nr_rings);
>> @@ -332,7 +319,7 @@ static int hci_dma_init(struct i3c_hci *hci)
>>  		return -ENOMEM;
>>  	hci->io_data = rings;
>>  	rings->total = nr_rings;
>> -	rings->sysdev = sysdev;
>> +	rings->sysdev = i3c_hci_sysdev(hci->master.dev.parent);
>>
>>  	for (i = 0; i < rings->total; i++) {
>>  		u32 offset = rhs_reg_read(RHn_OFFSET(i));
>> diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
>> index b3d9803b1968..b8d2a3d680f8 100644
>> --- a/drivers/i3c/master/mipi-i3c-hci/hci.h
>> +++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
>> @@ -184,6 +184,8 @@ void amd_set_resp_buf_thld(struct i3c_hci *hci);
>>  void i3c_hci_sync_irq_inactive(struct i3c_hci *hci);
>>  int i3c_hci_process_xfer(struct i3c_hci *hci, struct hci_xfer *xfer, int n);
>>
>> +struct device *i3c_hci_sysdev(struct device *dev);
>> +
>>  #define DEFAULT_AUTOSUSPEND_DELAY_MS 1000
>>
>>  int i3c_hci_rpm_suspend(struct device *dev);
>> --
>> 2.53.0
>>