Hi Per, On Tue, Jun 21, 2011 at 12:21 PM, Per Forlin <per.forlin@xxxxxxxxxx> wrote: > On 21 June 2011 07:41, Kishore Kadiyala <kishorek.kadiyala@xxxxxxxxx> wrote: >> <snip> >> >>> + >>> +static void omap_hsmmc_pre_req(struct mmc_host *mmc, struct mmc_request *mrq, >>> + bool is_first_req) >> >> I don't see the usage of "is_first_req" below. >> Is it required? >> > It is not required. It is only an indication that this request is the > first in a series of request. The host driver may do various > optimisations based on this information. The first request in a series > of jobs can't be prepared in parallel to the previous job. The host > driver can do the following to minimise latency for the first job. > * Preparing the cache while the MMC read/write cmd is being > processed. In this case the pre_req could do nothing and the job is > instead run in parallel to the read/write cmd being sent. If the > is_first_req is false pre_req will run in parallel to an active > transfer, in this case it is more efficient to prepare the request in > pre_req. > * Run PIO mode instead of DMA > * Maybe there can be power related optimisations based on if it is > one single transfer or multiple ones. Ok, thanks for making things clear. <snip> Regards, Kishore -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
