[PATCH 0/4] hw/sd: Improve performance of read/write/erase

[Christian Speich <c.speich@avm.de>]

This patch series improves the performance of read/write/erase operations
on sdcards.

This is done by increasing the maximum buffer size that is worked on.
From 1 byte (master) to 512 bytes (first commit) to larger than 512
(adma commit).

Testing on my system with fio I see the following rough performance 
values in MiB/s.

              read write readwrite 
       master:   6     6     3/  3
 first commit:  51    43    23/ 23
second commit: 392   180   144/143

Tested on a 2GiB raw image with:
  fio --filename=/dev/mmcblk0 --direct=1 --runtime=60 --time_based --bs=128k --rw={mode}

The adma values are somewhat unstable but always >100MiB/s, I'm not sure
why but I guess it has something to do with the host side caching.

For erasing the third commit changes the erase operation to write zeros,
as indicated by DATA_STAT_AFTER_ERASE in SCR.

The fourth commit allows erasure in large blocks, to speed it up
significantly. Erasing 2GiB now takes 0.1s instead of 26s.

Signed-off-by: Christian Speich <c.speich@avm.de>
---
Christian Speich (4):
      hw/sd: Switch from byte-wise to buf+len read/writes
      hw/sd/sdhci: Don't use bounce buffer for ADMA
      hw/sd/sdcard: Erase blocks to zero
      hw/sd/sdcard: Erase in large blocks

 hw/sd/core.c       |  16 +---
 hw/sd/sd.c         | 277 ++++++++++++++++++++++++++++++++++++++++-------------
 hw/sd/sdhci.c      | 102 +++++++++++---------
 include/hw/sd/sd.h |  13 +--
 4 files changed, 277 insertions(+), 131 deletions(-)
---
base-commit: e7c1e8043a69c5a8efa39d4f9d111f7c72c076e6
change-id: 20250912-sdcard-performance-b4-d908bbb5a004

Best regards,
-- 
Christian Speich <c.speich@avm.de>