[PATCH rtems-libbsd 2/2] st-sdmmc: Handle short not cache aligned buffers

[Christian MAUDERER]

Hello Gedare,

thanks for the review.

Best regards

Christian

Am 14.04.21 um 18:31 schrieb Gedare Bloom:
> These two look good if no one complains go ahead. (I'm not 100% on
> this libbsd stuff yet.)
> 
> On Wed, Apr 14, 2021 at 1:21 AM Christian Mauderer
> <christian.mauderer at embedded-brains.de> wrote:
>>
>> Possible data sources for SD driver:
>>
>> - mmc_sd_switch():
>>      - length: 64 byte;
>>      - buffer on stack
>> - mmc_test_bus_width():
>>      - length: 4 or 8 byte
>>      - buffer in program memory or on stack
>> - mmc_app_send_scr():
>>      - length: 8 byte
>>      - buffer from device ivar structure
>> - mmc_app_sd_status():
>>      - length: 64 byte
>>      - buffer from device ivar structure
>> - mmc_send_ext_csd():
>>      - length: MMC_EXTCSD_SIZE = 512
>>      - buffer from device ivar structure
>> - rtems_bsd_mmcsd_disk_read_write():
>>      - length: depends on read
>>      - buffer from rtems_blkdev buffer -> already aligned
>> - mmcsd_ioctl_cmd():
>>      - length: depends on call
>>      - buffer malloced, not aligned -> patched in RTEMS
>>
>> So the problematic buffers are only the ones up to 512 bytes. Copy these data
>> into a buffer to avoid that problem.
>> ---
>>   rtemsbsd/sys/dev/mmc/st-sdmmc.c | 14 ++++++++++----
>>   1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/rtemsbsd/sys/dev/mmc/st-sdmmc.c b/rtemsbsd/sys/dev/mmc/st-sdmmc.c
>> index e50b400a..4b202952 100644
>> --- a/rtemsbsd/sys/dev/mmc/st-sdmmc.c
>> +++ b/rtemsbsd/sys/dev/mmc/st-sdmmc.c
>> @@ -117,7 +117,8 @@ __FBSDID("$FreeBSD$");
>>   #define RES_IRQ_SDMMC 2
>>   #define RES_NR 3
>>
>> -#define DMA_BUF_SIZE CPU_CACHE_LINE_BYTES
>> +/* Maximum non-aligned buffer is 512 byte from mmc_send_ext_csd() */
>> +#define DMA_BUF_SIZE 512
>>
>>   #if 0
>>   #define debug_print(sc, lvl, ...) \
>> @@ -575,14 +576,19 @@ st_sdmmc_cmd_do(struct st_sdmmc_softc *sc, struct mmc_command *cmd)
>>
>>                  BSD_ASSERT(xferlen % (1 << blksize) == 0);
>>
>> -               if (xferlen < CPU_CACHE_LINE_BYTES) {
>> +               data = cmd->data->data;
>> +               /*
>> +                * Check whether data have to be copied. Reason is either
>> +                * misaligned start address or misaligned length.
>> +                */
>> +               if (((uintptr_t)data % CPU_CACHE_LINE_BYTES != 0) ||
>> +                   (xferlen % CPU_CACHE_LINE_BYTES) != 0) {
>> +                       BSD_ASSERT(xferlen < DMA_BUF_SIZE);
>>                          if ((cmd->data->flags & MMC_DATA_READ) == 0) {
>>                                  memcpy(sc->dmabuf, cmd->data->data, xferlen);
>>                          }
>>                          data = sc->dmabuf;
>>                          short_xfer = true;
>> -               } else {
>> -                       data = cmd->data->data;
>>                  }
>>
>>                  dctrl |= blksize << SDMMC_DCTRL_DBLOCKSIZE_Pos;
>> --
>> 2.26.2
>>
>> _______________________________________________
>> devel mailing list
>> devel at rtems.org
>> http://lists.rtems.org/mailman/listinfo/devel

-- 
--------------------------------------------
embedded brains GmbH
Herr Christian MAUDERER
Dornierstr. 4
82178 Puchheim
Germany
email: christian.mauderer at embedded-brains.de
phone: +49-89-18 94 741 - 18
fax:   +49-89-18 94 741 - 08

Registergericht: Amtsgericht München
Registernummer: HRB 157899
Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler
Unsere Datenschutzerklärung finden Sie hier:
https://embedded-brains.de/datenschutzerklaerung/