Re: [PATCH net 3/3] i2c: designware: support hardware lock for Wangxun 10Gb NIC

On Thu, Aug 29, 2024 at 05:15:42PM +0800, Jiawen Wu wrote:

On Fri, Aug 23, 2024 10:13 PM, Andy Shevchenko wrote:

...

On Fri, Aug 23, 2024 at 11:02:42AM +0800, Jiawen Wu wrote:

...

...

...

+static int i2c_dw_txgbe_acquire_lock(struct dw_i2c_dev *dev) +{

• void __iomem *req_addr;
• u32 swsm;
• int i;
• req_addr = dev->ext + I2C_DW_TXGBE_MNG_SW;
• for (i = 0; i < I2C_DW_TXGBE_REQ_RETRY_CNT; i++) {

Retry loops much better in a form of

unsigned int retries = ...; ... do { ... } while (--retries);

BUT... see below.

...

• writel(I2C_DW_TXGBE_MNG_SW_SM, req_addr);
  

• /* If we set the bit successfully then we got semaphore. */
  

• swsm = readl(req_addr);
  

• if (swsm & I2C_DW_TXGBE_MNG_SW_SM)
  

• 	break;
  

• udelay(50);
  

So, can a macro from iopoll.h be utilised here? Why not?

I need to write the register first and then read it in this loop. It does not seem to apply to the macros in iopoll.h.

I don't see how does it prevent from using read_poll_timeout() macro. You need to implement a body of the loop as a helper function that you supply into macro as a parameter.

...

...

• }
• if (i == I2C_DW_TXGBE_REQ_RETRY_CNT)

• return -ETIMEDOUT;
  

• return 0;

+}