On Fri, 2021-09-24 at 23:33 +0200, Bean Huo wrote: > On Fri, 2021-09-24 at 16:26 +0300, Adrian Hunter wrote: > > On 24/09/21 4:08 pm, Bean Huo wrote: > > > On Fri, 2021-09-24 at 15:17 +0300, Adrian Hunter wrote: > > > > > > > sdhci_writeb(host, count, > > > > > > > SDHCI_TIMEOUT_CONTROL); > > > > > > > } > > > > > > > The driver has detected that the hardware timer cannot > > > > > > > meet > > > > > > > the > > > > > > > timeout > > > > > > > requirements of the device, but we still use the hardware > > > > > > > timer, > > > > > > > which will > > > > > > > allow potential timeout issuea . Rather than allowing a > > > > > > > potential > > > > > > > problem to exist, why can’t software timing be used to > > > > > > > avoid > > > > > > > this > > > > > > > problem? > > > > > > Timeouts aren't that accurate. The maximum is assumed > > > > > > still > > > > > > to > > > > > > work. > > > > > > mmc->max_busy_timeout is used to tell the core what the > > > > > > maximum > > > > > > is. > > > > > mmc->max_busy_timeout is still a representation of Host HW > > > > > timer > > > > > maximum timeout count, isn't it? > > > > > > > > Not necessarily. For SDHCI_QUIRK2_DISABLE_HW_TIMEOUT it would > > > > be > > > > > > > > set to zero to indicate no maximum. > > > > > > yes, this is the purpose of the patch, for the host controller > > > without > > > quirk SDHCI_QUIRK2_DISABLE_HW_TIMEOUT, if the timeout count > > > required by > > > device is beyond the HW timer max count, we choose SW timer to > > > avoid the HW timer timeout IRQ. > > > > > > I don't know if I get it correctly. > > > > Why can't drivers that want the behaviour just set the quirk? > > > > Drivers that do not work with the quirk, do not have to set it. > > Adrian, > > We cannot add this quirk to every host driver. This is the difference > on the device side. In addition, I don't know what the maximum > hardware > timer budget for each host is. Even if you use the same SOC, the > maximum time budget on different platforms may be different. > > Assume that the maximum timeout time supported by the hardware timer > is > 100 milliseconds, but the maximum data transmission time required by > the device is 150 milliseconds. In most cases, data transfer will not > take so long. 150 is the maximum time under extreme conditions. This > means that the device just needs to complete a data transfer within > > 100ms and keep the data line busy. If we still use the HW timer, it > will trigger a DATA LINE timeout interrupt. > > This patch does not affect scenarios where the hardware timer meets > the > max data transmission time requirements of the device. It will still > use the hardware timer. Only when the device changes, will it switch > to > using the SW timer. > > Bean > Hi Adrian, Would you please review this patch again and is it possible to be accepted? Bean
