On Fri, Jan 02, 2026 at 12:47:04PM +0000, Bartosz Golaszewski wrote:

On Tue, 30 Dec 2025 17:40:33 +0100, "Michael S. Tsirkin" [off-list ref] said:

quoted

Reorder struct virtio_gpio_line fields to place the DMA buffers (req/res)
last. This eliminates the need for __dma_from_device_aligned_end padding
after the DMA buffer, since struct tail padding naturally protects it,
making the struct a bit smaller.

Size reduction estimation when ARCH_DMA_MINALIGN=128:
- request is 8 bytes
- response is 2 bytes
- removing _end saves up to 128-6=122 bytes padding to align rxlen field

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/gpio/gpio-virtio.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c
index 32b578b46df8..8b30a94e4625 100644
--- a/drivers/gpio/gpio-virtio.c
+++ b/drivers/gpio/gpio-virtio.c

@@ -26,12 +26,11 @@ struct virtio_gpio_line {
 	struct mutex lock; /* Protects line operation */
 	struct completion completion;

+	unsigned int rxlen;
+
 	__dma_from_device_aligned_begin
 	struct virtio_gpio_request req;
 	struct virtio_gpio_response res;
-
-	__dma_from_device_aligned_end
-	unsigned int rxlen;
 };

 struct vgpio_irq_line {
--

MST

Acked-by: Bartosz Golaszewski <redacted>

Thanks! There's a new API as suggested by Petr so these patches got changed,
but the same idea. Do you want me to carry your ack or you prefer to
re-review?

-- 
MST