Writing a pixel in VGA mode 12h (and VESA)

This is the code I am using at the moment which seems to work OK, even with banked VESA modes.

Code:

set_vga_mode:
        mov ax,12h
        int 10h
        mov dx,3ceh
        mov ax,205h     ;5=mode register
        out dx,ax       ;2=write mode 2
     ret

write_pixel_4bit:
        pusha
        push es
        mov bx,ax        ;save AL (colour)
        and bl,15
        mov ax,[bpline]  ;bytes per line
        mov di,cx        ;column
        mul dx           ;row*bytes per line = byte address
        shr di,3         ;column/8 = bit address
        add di,ax        ;byte that has the pixel (1 of 8 )
        ;here you would check for carry and switch banks for VESA
        mov ax,0a000h
        mov es,ax
        not cl           ;bits reversed, column<>bit
        and cl,7         ;bit position of pixel
        mov dx,3ceh
        mov ax,108h      ;8=bitmask register
        shl ah,cl        ;correct bit
        out dx,ax        ;?=bitmask
        cli
        mov al,[es:di]   ;load latch and ignore
        mov [es:di],bl   ;set the colour planes
        sti
        pop es
        popa
        ret

I set the mode and then set write mode 2 because that's all I am using, since it seems
to make it as easy to write a character (aligned at 8 bits) a line at once.

My thoughts are:
1. Is it correct? It seems to work (both bochs and my real computer).
2. It even seems to work with a VESA banked mode like 1024x768 even though my 8800GT says the mode is not VGA compatible.

I only want to support 16-colour graphics to make my VESA routines complete, but after reading parts of the "graphics black book" I'm not so sure what I'm doing...