| Message ID | Z0Iq9ex25MkwC_Cm@UBUNTU-PF54DSY0 |
|---|---|
| State | New |
| Headers | show |
| Series | mtd: rawnand: arasan: Fix double assertion of chip-select | expand |
Hi Maciej, On 23/11/2024 at 20:20:21 +01, Maciej Andrzejewski <maciej.andrzejewski@m-works.net> wrote: > When two chip-selects are configured in the device tree, and the second is > a non-native GPIO, both the GPIO-based chip-select and the first native > chip-select may be asserted simultaneously. This double assertion causes > incorrect read and write operations. > > The issue occurs because when nfc->ncs <= 2, nfc->spare_cs is always > initialized to 0 due to static initialization. Consequently, when the > second chip-select (GPIO-based) is selected in anfc_assert_cs(), it is > detected by anfc_is_gpio_cs(), and nfc->native_cs is assigned the value 0. > This results in both the GPIO-based chip-select being asserted and the > NAND controller register receiving 0, erroneously selecting the native > chip-select. > > This patch resolves the issue, as confirmed by oscilloscope testing with > configurations involving two or more chip-selects in the device tree. > Ok to me, can you please send a v2 with correct Fixes and Cc: stable tags, please? Thanks, Miquèl
diff --git a/drivers/mtd/nand/raw/arasan-nand-controller.c b/drivers/mtd/nand/raw/arasan-nand-controller.c index 5436ec4a8fde..7c97f421e382 100644 --- a/drivers/mtd/nand/raw/arasan-nand-controller.c +++ b/drivers/mtd/nand/raw/arasan-nand-controller.c @@ -1409,8 +1409,8 @@ static int anfc_parse_cs(struct arasan_nfc *nfc) * case, the "not" chosen CS is assigned to nfc->spare_cs and selected * whenever a GPIO CS must be asserted. */ - if (nfc->cs_array && nfc->ncs > 2) { - if (!nfc->cs_array[0] && !nfc->cs_array[1]) { + if (nfc->cs_array) { + if (nfc->ncs > 2 && !nfc->cs_array[0] && !nfc->cs_array[1]) { dev_err(nfc->dev, "Assign a single native CS when using GPIOs\n"); return -EINVAL;
When two chip-selects are configured in the device tree, and the second is a non-native GPIO, both the GPIO-based chip-select and the first native chip-select may be asserted simultaneously. This double assertion causes incorrect read and write operations. The issue occurs because when nfc->ncs <= 2, nfc->spare_cs is always initialized to 0 due to static initialization. Consequently, when the second chip-select (GPIO-based) is selected in anfc_assert_cs(), it is detected by anfc_is_gpio_cs(), and nfc->native_cs is assigned the value 0. This results in both the GPIO-based chip-select being asserted and the NAND controller register receiving 0, erroneously selecting the native chip-select. This patch resolves the issue, as confirmed by oscilloscope testing with configurations involving two or more chip-selects in the device tree. Signed-off-by: Maciej Andrzejewski <maciej.andrzejewski@m-works.net> --- drivers/mtd/nand/raw/arasan-nand-controller.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)