On 15/01/2025 07:20, Varadarajan Narayanan wrote:
> dwc3_core_init loops 'timeout' times to check if the IP block is out
> of reset using 'while (timeout--)'. If there is some issue and
> the block doesn't come out of reset, the loop will run till
> 'timeout' becomes zero and the post decrement operator would set
> timeout to 0xffffffff. Though the IP block is not out reset, the
> subsequent if check 'if !timeout' would fail as timeout is not
> equal to zero and the function proceeds with the initialization.
Nice catch, this is a nasty one.
>
> Use poll API instead to resolve this.
>
> Tested-By: Varadarajan Narayanan <[email protected]>
> Signed-off-by: Varadarajan Narayanan <[email protected]>
Reviewed-by: Caleb Connolly <[email protected]>
> ---
> v2: * Use poll API and remove the timeout variable based loop as
> suggested by 'Marek Vasut'
> * Drop 'Reviewed-by: Neil Armstrong' as the patch has taken
> a very different shape
> ---
> drivers/usb/dwc3/core.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a35b8c2f64..847fa1f82c 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -23,6 +23,7 @@
> #include <linux/delay.h>
> #include <linux/dma-mapping.h>
> #include <linux/err.h>
> +#include <linux/iopoll.h>
> #include <linux/ioport.h>
> #include <dm.h>
> #include <generic-phy.h>
> @@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
> */
> static int dwc3_core_init(struct dwc3 *dwc)
> {
> - unsigned long timeout;
> u32 hwparams4 = dwc->hwparams.hwparams4;
> u32 reg;
> int ret;
> @@ -610,15 +610,11 @@ static int dwc3_core_init(struct dwc3 *dwc)
> }
>
> /* issue device SoftReset too */
> - timeout = 5000;
> dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
> - while (timeout--) {
> - reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> - if (!(reg & DWC3_DCTL_CSFTRST))
> - break;
> - };
> -
> - if (!timeout) {
> + ret = read_poll_timeout(dwc3_readl, reg,
> + !(reg & DWC3_DCTL_CSFTRST),
> + 1, 5000, dwc->regs, DWC3_DCTL);
> + if (ret) {
> dev_err(dwc->dev, "Reset Timed Out\n");
> ret = -ETIMEDOUT;
> goto err0;
--
// Caleb (they/them)
