[PATCH] lpd: marvell: mark the indirect-access registers as volatile

In optimization level -O3, a sequence of VSR read/write operations
can be incorrectly optimized away as the compiler doesn't know the
underlying memory locations can change and react to read/writes.

So, mark the pointers used to read/write to the indirect-access
registers which access the VSRs with the 'volatile' keyword.

Test-cases:
----------

CFLAGS=-O2 (default)

    # make
    # LPD_DEBUG=1 ./lpd/usysident
    ...
    DEBUG: get_mv_indicator(): Data Out: '0x00000018'
    DEBUG: get_mv_indicator(): Data Out Enable: '0xffffffe7'
    DEBUG: get_mv_indicator(): Port Active Select: '0x2db6da8d'
    ...

CFLAGS=-O3

    # rm lpd/indicator_marvell.o
    # CFLAGS='-O3' make
    # LPD_DEBUG=1 ./lpd/usysident
    ...
    DEBUG: get_mv_indicator(): Data Out: '0x2db6da8d'
    DEBUG: get_mv_indicator(): Data Out Enable: '0x2db6da8d'
    DEBUG: get_mv_indicator(): Port Active Select: '0x2db6da8d'
    ...

CFLAGS=-O3 (patched)

    # rm lpd/indicator_marvell.o
    # CFLAGS='-O3' make
    # LPD_DEBUG=1 ./lpd/usysident
    ...
    DEBUG: get_mv_indicator(): Data Out: '0x00000018'
    DEBUG: get_mv_indicator(): Data Out Enable: '0xffffffe7'
    DEBUG: get_mv_indicator(): Port Active Select: '0x2db6da8d'

Signed-off-by: Mauricio Faria de Oliveira <[email protected]>
Fixes: efb9a4df3f88 ("lpd: Add support for Marvell HDD LEDs on S822LC for HPC")
---
 lpd/indicator_marvell.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lpd/indicator_marvell.c b/lpd/indicator_marvell.c
index ec2580a73f03..ace808dde53f 100644
--- a/lpd/indicator_marvell.c
+++ b/lpd/indicator_marvell.c
@@ -183,8 +183,8 @@ mv_munmap_bar5(void *bar5, int fd)
 static uint32_t
 mv_vsr_read(void* bar5, uint32_t vsr_addr)
 {
-	uint32_t *addr = (uint32_t *)(bar5 + mv_pci_bar5_vsr_addr);
-	uint32_t *data = (uint32_t *)(bar5 + mv_pci_bar5_vsr_data);
+	volatile uint32_t *addr = (uint32_t *)(bar5 + mv_pci_bar5_vsr_addr);
+	volatile uint32_t *data = (uint32_t *)(bar5 + mv_pci_bar5_vsr_data);
 
 	/* set address and read data */
 	*addr = vsr_addr;
@@ -204,8 +204,8 @@ mv_vsr_read(void* bar5, uint32_t vsr_addr)
 static void
 mv_vsr_write(void* bar5, uint32_t vsr_addr, uint32_t vsr_data)
 {
-	uint32_t *addr = (uint32_t *)(bar5 + mv_pci_bar5_vsr_addr);
-	uint32_t *data = (uint32_t *)(bar5 + mv_pci_bar5_vsr_data);
+	volatile uint32_t *addr = (uint32_t *)(bar5 + mv_pci_bar5_vsr_addr);
+	volatile uint32_t *data = (uint32_t *)(bar5 + mv_pci_bar5_vsr_data);
 
 	/* set address and write data */
 	*addr = vsr_addr;
-- 
1.8.3.1


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