stm32h7: sdmmc: write DCTRL after DTIMER/DLENR for non-data commands

commit 55183c0b2a82423835aaa0eee276357d9beae3e8
Author: Aidan MacDonald <[email protected]>
Date:   Tue Feb 24 20:33:27 2026 +0000

    stm32h7: sdmmc: write DCTRL after DTIMER/DLENR for non-data commands
    
    According to RM0433 the DCTRL register needs to be written
    after DLENR and DTIMER. This is respected for data transfer
    commands but not for non-data commands. Nothing bad seems
    to be happening because of this, but it seems wise to rectify
    the issue.
    
    Change-Id: I55d8f2c1994bff747e5978847fda57445f001b02

diff --git a/firmware/target/arm/stm32/sdmmc-stm32h7.c b/firmware/target/arm/stm32/sdmmc-stm32h7.c
index 014e5f6340..2fd9ff1cb4 100644
--- a/firmware/target/arm/stm32/sdmmc-stm32h7.c
+++ b/firmware/target/arm/stm32/sdmmc-stm32h7.c
@@ -260,6 +260,7 @@ int stm32h7_sdmmc_submit_command(void *controller,
     uint32_t maskr = CMD_ERROR_BITS;
     uint32_t cmdr = __reg_orf(SDMMC_CMDR, CPSMEN(1), CMDINDEX(cmd->command));
     uint32_t cmd_wait = WAIT_CMD;
+    uint32_t dctrl = 0, dtimer = 0, dlenr = 0;
 
     void *buff_addr = cmd->buffer;
     size_t buff_size = cmd->nr_blocks * cmd->block_len;
@@ -317,7 +318,6 @@ int stm32h7_sdmmc_submit_command(void *controller,
             panicf("%s: buffer too big", __func__);
 
         /* Set block size */
-        uint32_t dctrl = 0;
         uint32_t dblocksize = find_first_set_bit(cmd->block_len);
         if (dblocksize > 14 || (cmd->block_len & (cmd->block_len - 1)))
             panicf("%s: incorrect block size", __func__);
@@ -341,11 +341,8 @@ int stm32h7_sdmmc_submit_command(void *controller,
         reg_assignlf(ctl->regs, SDMMC_IDMACTRLR, IDMAEN(1));
 
         /* Use a 10 second timeout (DTIMER is in units of bus clocks) */
-        reg_varl(ctl->regs, SDMMC_DTIMER) = 10 * ctl->bus_freq;
-        reg_varl(ctl->regs, SDMMC_DLENR) = buff_size;
-
-        /* DCTRL must be written last */
-        reg_varl(ctl->regs, SDMMC_DCTRL) = dctrl;
+        dtimer = 10 * ctl->bus_freq;
+        dlenr = buff_size;
 
         /* Enable data phase */
         reg_vwritef(cmdr, SDMMC_CMDR, CMDTRANS(1));
@@ -356,16 +353,17 @@ int stm32h7_sdmmc_submit_command(void *controller,
     {
         /* Disable data transfer */
         reg_assignlf(ctl->regs, SDMMC_IDMACTRLR, IDMAEN(0));
-        reg_varl(ctl->regs, SDMMC_DLENR) = 0;
-        reg_varl(ctl->regs, SDMMC_DCTRL) = 0;
 
         /* DTIMER is the wait time for the busy signal */
         if (cmd->flags & SDMMC_RESP_BUSY)
-            reg_varl(ctl->regs, SDMMC_DTIMER) = 1 * ctl->bus_freq;
-        else
-            reg_varl(ctl->regs, SDMMC_DTIMER) = 0;
+            dtimer = 1 * ctl->bus_freq;
     }
 
+    /* Set data transfer registers */
+    reg_varl(ctl->regs, SDMMC_DLENR)  = dlenr;
+    reg_varl(ctl->regs, SDMMC_DTIMER) = dtimer;
+    reg_varl(ctl->regs, SDMMC_DCTRL)  = dctrl;
+
     /*
      * Set CMDSTOP bit for CMD12 (stop transmission) command;
      * this is needed to stop the DPSM in case of an error in
-- 
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