On 12 June 2017 at 11:26, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> On 12/06/17 11:49, Ulf Hansson wrote:
>> The MMC_CAP2_HC_ERASE_SZ is used only by a few mmc host drivers. Its intent
>> is to enable eMMC's high-capacity erase size, as to improve the behaviour
>> of the erase operations.
>>
>> However, for eMMCs supporting trim/discard, the MMC_CAP2_HC_ERASE_SZ
>> becomes somewhat redundant. This because trim/discard operates on sectors
>> and these commands takes precedence over erase commands, when supported.
>>
>> In addition, we should really avoid software configuration options that
>> isn't necessary, but instead strive to deploy common behaviours. For these
>> reasons, let's remove the capability bit for MMC_CAP2_HC_ERASE_SZ and the
>> corresponding behaviour.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>> ---
>> drivers/mmc/core/mmc.c | 3 +--
>> drivers/mmc/host/sdhci-acpi.c | 1 -
>> drivers/mmc/host/sdhci-brcmstb.c | 3 ---
>> drivers/mmc/host/sdhci-pci-core.c | 4 +---
>> include/linux/mmc/host.h | 1 -
>> 5 files changed, 2 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index e504b66..d1a6d74 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1655,8 +1655,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>> * If enhanced_area_en is TRUE, host needs to enable ERASE_GRP_DEF
>> * bit. This bit will be lost every time after a reset or power off.
>> */
>> - if (card->ext_csd.partition_setting_completed ||
>> - (card->ext_csd.rev >= 3 && (host->caps2 & MMC_CAP2_HC_ERASE_SZ))) {
>> + if (card->ext_csd.partition_setting_completed) {
>
> PARTITION_SETTING_COMPLETED was added in eMMC v4.4 but ERASE_GROUP_DEF was
> added in eMMC v4.3, so this doesn't work for v4.3 devices.
>
> Why not enable it always? i.e.
>
> if (card->ext_csd.rev >= 3) {
Yes, that makes sense! Thanks for spotting this!
However, that actually means this didn't work as expected for hosts
that didn't specify MMC_CAP2_HC_ERASE_SZ.
[...]
Kind regards
Uffe
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